くれれば and くれば difference

You're looking at two different verbs/grammars (くる and くれる), so even though the end result appears to be the same with some translation tools (cough cough google), there is actually a difference between the two.

Let's start with the first sentence.

教えてくれば感謝

The grammar being used here is the ～て + くる grammar. According to 'A Dictionary of Basic Japanese Grammar', くる functions as "an auxiliary verb which indicates the beginning of some process or continuation of some action up to a current point of time."

This means that 教えてくる can be translated as begin to teach.

～ば is a grammar formation for 'if.' As an irregular verb, くる joins with ば in a way unique from other verbs. In this case, くる + ば = くれば. We'll have more on the conjugation here later, but let's get on with what this means.

This means that 教えてくれば means if (implied person) begin(s) to teach.

Therefore the first case would be something like: (I'd) be grateful if (you) started to teach. Depending on context, who the speaker is talking to, and a number of other factors, the person doing the teaching and the person doing the thanking will change. However, that's the gist of what's happening.

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教えてくれれば感謝

The grammar being used here is ～て + くれる. According to 'A Dictionary of Basic Japanese Grammar' we can understand this grammar as "someone does something as a favor to the first perso or to someone with whom the speaker empathizes."

This means that 教えてくれる can be translated as teach as a favor to me.

Once again, we have the ～ば form of 'if.' Using this guide for conjugation rules, we can see that くれる + ば = くれれば. The conjugation here is distinct from the previous example.

This means that 教えてくれれば means if (implied person) teach(es) as a favor to me.

Therefore, this second case would be translated something like: (I'd) be grateful if (you) teach as a favor to me. Again the people involved and meaning of the sentence will change with context, who is speaking, and other factors.

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If you oversimplify these translations to make them sound more natural in English, you can run into cases where the translations of both phrases are the same (like you see in google translate). Be careful to not trust translation tools implicitly, as sometimes meaning is lost in translation, especially if you don't pay attention to the grammar/words at play in the phrases you are translating.

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Note:

This assumes that you are using 教える as to teach. The same principles also apply if you use the meaning to tell/inform.