Safety Razors: In Wet Shaving, a safety razor is typically a razor handle that accepts one double edge safety razor blade that is replaceable. The blades are normally replaced by unscrewing the razor head.
Single Edge Razor: A single edge razor is a cut through razor. It is so called as the razor blade it accepts only has a blade on one side.
Adjustable Safety Razor: An Adjustable Safety Razor has a variable gap between the razor blade and the comb on the razor handle. The benefits of an adjustable safety razor is that fewer passes are needed, even with a thick beard. This type of razor are more aggressive than standard double edge safety razors as sold here.
Closed Comb Safety Razor: A closed comb safety razor is a razor with a comb on the head that has indentations rather than gaps.