For non etops flights, the plane needs to fly not further than the distance flown in 60mins at the one engine inop cruising speed in still air, which are:
B737-800 Non Winglet = 395nm
B737-800 Winglet = 400nm
B757-200 = 400nm
So having winglets on the 737 does (just!) make a difference whereas on the 757 it doesn’t.