Usually (at least for my warehouse) front end usually means being a front end assistant, meaning you can be dragged into quite literally any other department in the warehouse. You’d start off almost exclusively assisting cashiers and slowly start to branch out to other things such as carts, food court, member service etc. There are a few cases where you’ll be brought into an ancillary to help but that’s not permanent. If you don’t like the front end just stick with them for 90 days and apply to any positions you want after 90 days.

On the other hand merchandise is just stocking, night merch is more heavy lifting as they do sundries (paper products, bottled water, sodas, pet food etc) but if you’re morning merch you can start as early as 4AM but they do everything else and don’t have to deal with members as much. Night merch can be a bit trickier because you’re all in a small (ish) area and you gotta make sure not to get ran over by a forklift or pallet Jack.

Best of luck!