basically, there are two kinds, as I see it. One is the child does something that angers the parent, and without much consideration or thinking about it, the parent smacks the child with a lot of anger, sometimes surprising the kid, but usually pretty quickly. And the message is "you made me angry, and I'm smacking you for it." Maybe on the butt, maybe somewhere else.

The other kind, which people criticize as "hitting when you're calm" is "your behavior was out of line, and as a consequence, we're going to talk about this for a minute (sometimes longer) and then you will lie over my lap and get spankings on your butt in a way that is moderated and not with crazy force or anger.

It's a huge, huge difference.