By Application
drill bits wholesale's auger bits generally drill cleaner holes with smoother sides and less chipping. They are commonly used for general wood drilling in construction, carpentry in gardening and many other fields.
Spade drills have rougher sides and are therefore used for areas that will be covered. For example, these bits are often used when installing electrical conduit or water pipes through a wall, as the holes will be covered with a better finish.
By shape and design
Design is a significant difference between these two bits.
An auger bit is a helical drill with a threaded tip on the front and two chisels on each tip. These chisels are responsible for planing the wood.
Spade bits are flat. They need a comfortable design, shaped like a shovel or paddle, with two sharp lips on each end and a pointed unthreaded guide tip.
By purpose
The bit needs downward pressure when drilling to make it more comfortable. The tip of the thread pulls the drill down and creates an automatic drive mechanism that takes effect immediately, even if just the load of the drill pushes down.
This is not the equivalent of a shovel position. Their tips may be sharp, but they are not threaded, so they don't drive themselves. So you want to dig fast with more downward force. Using only the load of the drill bit, drilling can take a short time.