Repro mag question

[Ice]

This may have been asked before but I did a search on "repro magazine" and nothing turned up. Sorry if its a dup.

I know that Mec Gar mags hold 8 cartridges while the other brand holds 7. My question is, why the difference? Both brands are the same length. Is the difference the spring, the follower or what.

Thanks for your help.

Charlie