"Compared with" vs "Compared to"—which is used when?

Use "compared with" when you are looking for differences.

E.g. CEO’s now earn 419 times the pay of blue-collar workers, compared with 42 times their pay in the 1980's.

Use "compared to" when highlighting (or comparing) the similarities of one thing to another.

E.g. The human heart can be compared to a pump.

I have always found this distinction to be counterintuitive. "With" suggests closeness, i.e., similarity; while "to" connotes distance, as in "going to".

Therefore, the way I always remember the difference is: They are the opposite of what they should be.

We compare with when we are going to look for differences...My English is better compared with it was in 2013...that is,I can see a difference in my English....

We compare to when we see similarities... Rio De Janeiro City is compared to California... This sentence means that we can find some similarities between Rio De Janeiro and California.

Bryan Garner, Garner's Modern American Usage, fourth edition (2016) provides what I take to be the current (and traditional) formal prescriptivist view among U.S. usage authorities of when to use compered with and when to use compared to:

compare with; compare to. The usual phrase has for centuries been compare with, which means "to place side by side, noting differences and similarities between" {let us compare his goals with his actual accomplishments}. Compare to = to observe or point only to likenesses between {he compared her eyes to limpid pools}.

But one of the most familiar "comparisons to" in English literature, Shakespeare's Sonnet XVIII, appears to flout that supposed rule in the first two lines:

Shall I compare thee to a summer's day?

Thou art more lovely and more temperate:

If we take Garner's rule at face value, Shakespeare, since he wasn't merely saying "You are like a summer's day," should have said

Shall I compare thee with a summer's day?

He puts the day and the beloved side by side and promptly concludes that the beloved is more lovely and more temperate. Those, in a nutshell, are Garner's conditions precedent for using compare with. And Shakespeare can't argue that "The meter made me do it," because with is just as unstressed as to. Either Shakespeare bricked his choice of preposition or this centuries-old rule is less honored in the real world than Garner and others would have us believe.

There is a third possibility, though: In line 1 of the sonnet, Shakespeare may be using compare to in its approved sense of "liken"—in effect saying, in the first two lines, "Shall I liken you to a summer's day? Nah, you're better than a summer's day." But this interpretation takes us only so far: by saying in line 2 that his beloved is more lovely and more temperate than (that is, different from) a summer's day, Shakespeare is unmistakably comparing the beloved with the summer's day, according to Garner's guidelines for distinguishing between compared with and compared to.

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An Ngram chart of "compared to" (blue line) versus "compared with" (red line) versus "in comparison to" (green line) versus "in comparison with" (yellow line) shows considerable change in the phrases' relative frequency of use in published writing since 1920:

The lines in the graph show compared with breaking away from compared to in frequency of use around 1760 and then steadily increasing its advantage until about 1920; then compared to begins a very brisk ascent in frequency that catches up to compared with (which has been in something of a decline since about 1960) around 1980, and continues to put distance between it and its rival over the next 25 years. Meanwhile, in comparison with opens a small but consistent lead over in comparison to by 1800 and for the next 140 years increases the advantage. But around 1940 the two lines begin converging, and at about the turn of the millennium they meet.

The line graphs in the Ngram chart suggest either that people now use compared to in the sense of "liken" far more often than they did a century ago or that the rule specifying when to use compared with and when to use compared to is fading from actual usage in published content. I think that the second explanation for the change in the Ngram data is far more likely than the first to be true.

It is certainly possible that the preference for compared to in instances in which the meaning is "likened" remains fairly strong, although there is no easy way to confirm this possibility. But the preference for compared with in instances in which the meaning is "examined side by side" seems to be in decline. The confluence in frequency of "in comparison with" and "in comparison to" (also shown in the Ngram chart above) offers some circumstantial weight to this hypothesis, since "in comparison to" seems never to have had a "liken" sense, as "compared to" sometimes does.

I expect the trend away from observing and enforcing the traditional compared with/compared to distinction in connection with the meaning "examined side by side" to become even more general as the involvement of copy editors in the publishing process continues to diminish.

I have been around this question many times before, and as I hesitate myself when it comes to explaining the differences"if there is any" between the two, I'll try to say what I have red in grammar books and hear in day to day conversations.

When making an analogy , or indicating that one thing resembles another " compare to is obligatory" so,

"He compared her tongue to a razor blade" means the man believes she has a tongue as sharp as a razor blade.

Same as in " She is such a great singer some people have even compared her to witney houston" Means she is so good at singing her voice is or could be as good as witney houston's.

When a negative auxiliary comes before "compare" "With" is more common in british English. So, " she doesn't compare with witney houston" " this coffee doesn't compare with the one they make at Sam's"

Such difference doesn't seem to be important in American English.

When Compare is used in the past participle form to introduce a Subordinate clause, With is more common in British English and To is more common in American English. So,

American English:

"Compared to my house, yours is huge"

"Your hair is silky compared to mine"

British English:

"Compared with my house,yours is huge"

"Your hair is silky compared with mine"

And finally, I think it is clearer to use" Compare with" when something annoys you because it makes you feel or look less important. For instance :

my mother is always comparing me with My cousins; she knows I really hate that !

Although somebody could also Compare someone or something To someone or something else in a positive way, it could still be irritating to you. For instance:

My mom is always comparing me to my cousin; I don't care whether we look alike or not, I just hate that

If in doubt, I would suggest sticking to "Compare to" which seems to be suitable for most cases.

I want to make something clear

I'm not a native speaker nor a teacher . All the content I'm posting here is material I have taken from dictionaries and personal opinions.

Standard English would have you use to compare with in an academic setting so as to differentiate between two things. The same context of style would require that you say to compare to if to show similarities between two things. In casual English however, either one works just fine and is considered standard English usage, again, given said register. This is backed up by several special-usage dictionaries as well as unabridged lexicons.

In reality, why this is the case is just a confusion.

The prepositions to and with do not frequently show difference, and so to impose difference versus similarity on said prepositions seems silly. I think a far better preposition of difference would be against or even from, even though no one would ever say to compare something against or to compare something from. This therefore leads to my point, which is that the confusion is a common one for we lowly humans: Parameters. The real issue is outside the box of both prepositions, and lies instead with the main meaning of to compare. To be comparable carries with it the implicit indication that two things are alike. Not unalike. This is why no one compares oranges to cockroaches. To contrast, however, connotes the opposite, and in my view is a far more appropriate word to use, which also incidentally rids us of the otherwise pointless question as to which preposition is "right." For most people, as seen by the question itself, the difference is one that leads to confusion, not precision, and probably arguments more often than anything.