Although drill bits come in specific sizes, not all 3/8″ bits do the same thing!
Brad Point Bit
The Brad Point bit (also known as lip and spur bit) is a precision drill bit. Due to it’s sharp point on the end, it makes it easy to be more exact in your drilling. This is my drill bit of choice. If I have it on the drill press, it’s easy to spot right where the bit will make contact and bore, without it dancing around on the wood first.
These are another precision bit. They are the precision bit equivalent to the spade bit. If you need to drill out a larger hole, with a nice finish, this would be your best option. Often used to drill holes for cabinet hardware installation.
Spade bits are not a precision bit. Although they do have the sharp tip, they don’t act like a brad point bit. The spade bit is often used for rough jobs. It is very common to see a lot of splintering when you use one of these. Not a bit you’ll have much use for if you have a forstner bit set.
Some projects it’s nice to have the screw inset into the wood, instead of visible. The way to get that look is with a countersink bit. This bit would be used with a standard screw. Notice how the screw head shape and the countersink bit shape match. The screw will sit nice inside your countersinked hole.
Does the same job as the countersink bit. Difference is, it leaves a flat surface on the bottom. Compare the shape of the two. While the countersink is a slanted shape, the counterbore is flat. If you are willing to buy the ______ screws, and you want your screw to fit down in flush, you should opt for the counterboring bit.