preferire...a...?
Non sempre i giovani preferiscono la discoteca al teatro.

Is it that the verb preferire is used with 'a' to express a comparison, i.e. preferire A a B = to prefer A than B ?

Question

preferire...a...?
Non sempre i giovani preferiscono la discoteca al teatro.

Is it that the verb preferire is used with 'a' to express a comparison, i.e. preferire A a B = to prefer A than B ?

Answer

Yes it is a comparison. preferisco A a B (or: A piuttosto che B; A riespetto a B)
But the comparison could even be implicit sometimes (just like in english):

-"vuoi un caffè?" (would you like a coffee?)
-"grazie, preferisco un bicchiere di vino" (Thanks, I'd prefer a glass of wine)

So it's just like "to Prefer" in english, it always expresses a comparison, even if not specified in the sentence.