Gate Checking will tag it through to the final destination as hold baggage. You’ll not see it again until you arrive at your destination, generally speaking (separate ticketing and long connections over 12 hours will require retrieving the gate-checked bag and checking it in again).

Valet checking they’ll generally give you a tag to affix and often either have you position the bag on a trolley or area or take the bag down the jetway to the ground ladder door. These bags will generally be brought up the ground ladder to you while you remain waiting in the jetway outside of the cabin door. At some locations they’ll bring a cart with the valet bags and you retrieve them from that (e.g. LAX Eagle’s Nest or smaller airports where you disembark onto the apron).

Then you proceed airside normally to your ne t flight with the valet bag now cabin baggage, as your next flight is on a 75L.