At the tips of the wings and at the trailing edge of the wings vortices will form when a wing is surrounded by nothing but air. Closer to the ground (typically less than a wingspan of the ground) these vortices start to form but are then interrupted by the ground. This results in an increase in lift and a very strong reduction in drag. The upshot of this is that in groundeffect a powered aircraft uses much less energy to move. Several bird species (mostly the bigger water birds) know how to exploit this as well.

The aircushion of the hyperloop is more like an air hockey table. It also reduces drag but that's drag from the surface of the table rather than from the air. Think of it as a two dimensional air bearing.

Apropos wingtip vortices: that's the reason lots of large planes are now equipped with winglets, these help to stop the formation of those vortices decreasing drag and increasing lift. Some larger windmill manufacturers use them too with the same goal, but in a windmill this translates to more power produced at the same windspeed rather than less fuel consumed in a vehicle.