There are basically two different categories / types of stain: one is acrylic and the other is alkyd. Depending on what results you desire for your wood deck determines the types of stain you choose. If you are looking for an alkyd stain to preserve the wood look a wood preservative / stain and if you are looking for a stain that would leave a layer of protection on top of the wood choose acrylic. Conversely the opposite is also true; acrylics do not penetrate much into the wood and alkyds do not leave much of a layer on the outside of the wood.
Acrylics are quite popular being water-based (easy cleanup), low-odor with reasonable performance. Thus if you are looking for a finish that you could walk on with your stocking feet, or slide furniture on; acrylics leave a coating on top of the wood. The other simplistic character of acrylics is when it peels, cracks or blisters from the foot traffic, sliding things on it; it is easy to spot and fix.
Alkyds on the other hand soak into the wood and do not leave much of a film on the wood. Most of the stain vehicle (synthetic resin) goes into the wood to protect the interior wood fibers. Not much of the stain is left on the outside of the wood, so once scratched the protection is left up to the sealed interior wood fibers to protect the wood’s integrity.