What makes an RPG an "ensemble cast" Vs. one with a defined Main Character

[Galuf]

I posted this in general RPG, though my examples are all from FF. It might sound like a silly question, maybe it is idk, also I probably got the term wrong but I'll explain in a sec.

So people pretty much agree FFVI is a game with no real main character, it's a game that's all about the individual characters, which is something I really enjoy about the game. (You could argue Kefka is the main character, but for sake of this he is just the reason everyone's together in the fight)
However, when it comes to games such as FFV, FFXII and FFXIII, people always define those games having main characters (Bartz, Vaan, Lightning). I am curious why those games aren't regarded like FFVI and being seen as more of an ensemble rather than just 1 main character.
As someone trying to write a story, I am attempting to make it be seen like FFVI and not like XII and this question ocurred to me. If you ask me, I do view all those games similarly, but most of the FF community does not.

Also I made this question on the forums because Wolf Kanno is deeply philosophical and has words of wisdom and detail, and also Fynn, and also half the people on here. Which is like 6 but still.