In the Sicilian we get pretty much the same themes that we already know from 1… e5. Most lines in the Sicilian are based on attacking the e4-pawn with Nf6, therefore the Sicilian is typically more aggressive than the attempts to trade off the e4-pawn. I will not go into details here and just mention the underlying strategic themes.
A. Alekhine-Theme (Nimzowich)
B. Pirc-Theme (Dragon)
C. Petroff-Theme (Sveshnikov)
White on the other hand can also try to follow typical patterns known from 1… e5: