I think the key difference is that the Toa Mata/Nuva were always Toa. We see, early on when their memories are mostly wiped, that they have some childish tendencies. By contrast, the Toa Metru were Matoran who were turned into Toa.
The other problem, though, is that the Matoran we see in MNOG ans some of the novels are a lot more adult like then the Matoran of the films shrug
I have always thought that their mask powers could be very reminiscent of their personalities.
Vakama didn’t want to stand up to his responsibilities and just wanted to be a nobody really.
Nokama was a good communicator and listener
Onewa was a bit of a bully who could force others to do things
Matau I think had the most complexone. He always played the joker/over confident type but we see in WoS that he does have a lot of sincerity about him. He is good at pretending being something he wasn’t.
Not too sure for Nuju or Whenua but I’m sure their is a collectiong.