1301 Tac has an 18" barrel w/3" chamber, ghost ring sights, 3" receiver, and comes with the Pic Rail installed.
1301 Comp has 21" or 24" barrels w/3" chambers, vent rib and bead sight, 3.5" receiver (bigger loading port), receiver is drilled for pic rail but it is not included ($65 option from Beretta).
Both have 5 round magazines, but a variety of vendors make magazine extensions.