Well obviously the stainless bolt offers better corrosion protection, however, where bolts need to be really tight or have great tensile load on them(being pulled apart) high tensile should be used instead.

Many High Tensile bolts will have a number of raised strokes formed in the head of the bolt. Three or five are common and usually form a reverse triangle or reverse heptagon

High strength tensile bolts are used for extreme projects the types of things you cannot risk falling apart. They are typically made out of steel.

14.15

what are the properties of a high tensile brass