It may be that the places offering the longer classes are furnishing you not only with lessons, but some additional climbing time with a belayer (if it's roped).

If you don't have someone to belay you, then roped climbs can't be done. You can boulder.

Bouldering can be done alone, and requires more upper body strength. Bouldering you don't go as high, and the routes are often horizontal or going up and over (either across a ceiling or topping out on top of a "wall/boulder").

Top roping is more about your legs, requires a partner/belayer, and is more vertical.

Both can involve overhangs (walls that come out toward you).

It really depends on what the gym has to offer and what you want to try.