We call them billets, and there’s literally hundreds. You don’t get to hold one until you’re an upperclass, but then most mids will have a different billet each semester. The ubiquitous one is the squad leader; As an SL your job is to ensure that the ~10 mids in your squad are meeting their various requirements, whether that’s academics, ProDev, conduct, etc. Each company also has its Platoon Commanders, XO and CC whose job is to relay information from the Company Officer and enforce the CO’s expectations. Then there’s positions relating to academics, planning events, writing watchbills, drill and ceremony, protocol, conduct, honor, maintenance, and many more.
Then of course you have the “Striper” billets like Batt Commander, who’s the Battalion Officer’s liaison to his/her midshipmen, all the way up to Brigade Commander who “leads” the Brigade, acting as a liasion between the Deputy Commandant and the rest of Midshipman leadership. Important to note that despite the names, these higher level billets are mostly symbolic. Brigade Commander leads parades/formations and introduces speakers at events, but they aren’t setting the actual policies. They exist as a sort of figurehead and also ensure that there’s smooth communication between the mids and officer leadership. Nonetheless these billets are highly competitive and are looked very favorably upon by Academy leadership and even outside assessors such as grad school admissions offices.