It depends on the rules. A sweepstakes requires no skill and the winner is selected at random. Say the Chamber of Commerce mixer is at the bank. Everyone attending (open to the public) gets a ticket and a winner is drawn for a prize. It’s a game of chance to be selected, it is a sweepstakes. Same gathering, but everyone attending answers some questions and the winners group is drawn down to one winner of the gift, that is a contest because they had to do things first which eliminated others. There was an element of skill. A contest lacks the element of chance.
A table full of things to be picked up and taken is nothing if offered to everyone and anyone, and could be a bonus if offered to depositors only and worth more than $10.