The Hyperloop uses a low pressure tunnel, that's critical and the system would not work with a vacuum tunnel. The air in the tunnel is blown below the car to provide a low friction interface, much like an air hockey table (but with the puck providing the air, not the table). Linear induction motors in sections of the track accelerate or decelerate the cars, with gliding in between.
This is a new idea, and it's a highly useful idea because the vast majority of the track is just a pressure vessel, while the friction reducing components are fairly low tech and on the pod and the acceleration components are only on small sections of track, and potentially solar powered during peak hours. This lowers the cost of construction enormously while enabling speeds approaching that of commercial air travel.