I think you're mistaken on that. All Chevy big blocks and small blocks I've seen have the distributor in the back. The way to tell the difference (if you can't tell by eye-balling the dimensions) is the big blocks have 7 bolts holding the valve covers whereas small blocks only have 4.

As for the topic at hand, I believe it was a term Chevy started waaaaay back in the 60s when GM actually made more than one motor.

This is an occasional topic on the Viper forums. I avoid confrontation by simply referring to it as a "big cube motor". Nobody with any brains would dispute 488cid as being big cubes.