Next is telling us at least two more things:
In most cases, after making these three selections, Select-A-Screw will have narrowed your search to just a few screws. As you select each of these four attributes, you will notice the number of screws shown decreases. With each selection, Select-A-Screw goes to work.
The difference between a traditional wood screw and a modern production screws is found in the sizing differences between the diameter of the screw shank and the screw threads.
Traditional Wood Screws - The shank diameter on this screw exactly matches the outside dimensions of the threads. Threads on these screws are deeper near the point and begin to shallow as they get closer to the unthreaded shank or screw head. Tapered drill bits are needed with this type of screw as the pilot hole should fit the outside shank diameter of the screw almost perfectly. Creating this tight fit on traditional wood screws yields maximum holding power.
Modern Production Screws - The shank diameter is actually smaller than the major diameter but larger than the minor diameter. The overall reduced shank diameter results in a deep thread profile offering great holding power. Drilling a pilot with a straight drill bit yields excellent results because the shank of the screw is straight through out its entire length. The advantages of this are that straight bits do not require the same critical depth control needed with a tapered bit.