Sting and thud
sting <------------------------------> thud
Stingy spanking implements produce a sharp sensation that is mostly felt on the skin. Thuddy implements, on the other hand, penetrate into deeper tissues and muscles. As a rule of thumb, the heavier an implement is, the thuddier it is.
Some spankees have a preference for sting while others prefer thud, and yet others like both, or implements in the middle of the spectrum that combine sting with thud, or getting a stingy implement first and a thuddy later, etc.
Thin stingy implements, such as canes, tend to produce welts and, in extreme cases, can break the skin. Thuddy implements, such as wooden paddles and heavy leather implements such as straps or belts, tend to leave bruises and, in extreme cases, can do damage to bones (such as the pelvis or coccyx) or nerves.