one is on the floor and runs along the floor of my room, the other is against the wall and looks like it drops straight down. is one for heat and the other for ac?
No. More than likely the one that is on your floor is your heat/ac vent. The one on your wall is most likely the return vent that takes air back to your HVAC unit for recirculation, or outside.
One might be to bring air to your room and one to take it back to become reheated and come out the other vent. But you could also be right I'm no expert.