Mainly that X-Wing Luke is in the orange jumpsuit with black boots and gloves. Snowspeeder Luke has a poofy orange jacket (you see Luke grab it in the movie when 2-1B tells him good luck) that goes over the jumpsuit, poofier pants, and tan colored moccasin shoes and gloves, and sometimes a thermal hood under the helmet. It's all really minor differences.
Thinking of the poll, a 3 pack of Bespin Guards (white, black, Asian) and a 2 pack of Ugnaughts sounds about perfect for online exclusive sets next year.