Difference between boolean and boolexpr?

Hi, what's the difference between boolean and boolexpr? It seems like a simple boolean could be used for everything. I guess this also leads to the question, what is boolexpr used for?

boolean is a Jass type that can be true or false.

boolexpr is a handle, a wc3 object that points to a boolean function, Jass' lack of native function pointers forced blizz to do this kind of hack for conditions and enum filters.