What's the difference between the enumerate and enumitem packages?

use enumitem (I wrote enumerate)

The enumitem package is far more flexible when compared with enumerate. The latter provides an optional argument where you can specify the item number format using a generic representation while the former provides a key-value interface where one can specify number format representation in addition to a host of other list-related settings (or perform these settings globally). Here are two examples:

• Parenthesized lowercase roman numerals:

    % enumerate interface
    begin{enumerate}[(i)]
      % Your list here
    end{enumerate}
  
    % enumitem interface
    begin{enumerate}[label = (roman*)]
      % Your list here
    end{enumerate}
  

• Bracketed uppercase alphabetic characters

    % enumerate interface
    begin{enumerate}[{[A]}]
      % Your list here
    end{enumerate}
  
    % enumitem interface
    begin{enumerate}[label = {[Alph*]}]
      % Your list here
    end{enumerate}
  

The interface provided by enumitem is more intuitive and verbose (you specify label explicitly, including the counter representation format Alph rather than A). Additionally, enumitem provides a host of other options, including

• separate label and ref keys for alternative references to labels,
• spacing adjustments (vertical and horizontal),
• in-line list enumeration,
• list continuation,
• new list style generation,
• ...

In short, enumitem provides a modern, user-friendly, key-value interface to many list manipulations, while enumerate is only geared towards short-hand list representation.