Question about unlocking vs. adding actors

Dooki

I've been studying the "unlock level" demo by Zeppelin. Took me a while to figure out the he used one actor for the level button, then unlocked it to add in other "level" graphics and tweaked game attributes. From what I was told unlocking an instance creates size because you are opening up the data from the instance. (Not the technical term but I get the idea)

Q: which is larger? Unlocking an instance six times or creating six separate buttons?
Thanks!