Crazy English language. Some terms may be regional too.
A beating implies severe hitting. Bruising, bleeding possibly concussion or broken bones.
A "spanking" is done more out of love. I would never "beat" a child. I did "pop" my child on the behind a couple times. A "pop" is more of a type of spanking. Spankings were often shortly followed by long talks and lots of hugs!
When used in reference to corporal punishment such as "The child recieved a paddling at school for bad behavior."
This means a couple "hits" on the buttocks with a wooden board (a paddle). Never hard enough to leave marks or bruises and not on bare skin.
The paddles were usually 16-18 inches long and about 4 inches wide.
This is true also.
"You row a boat with a paddle."
I hope I did not confuse you further!