I think the distinction is whether it’s the character being big or the performer
Like the Steve Martin/Dan Akroyd wild n crazy brothers are characters- Latka and Rev Jim, while wacky are still characters
Mary Catherine Gallagher is a character
Mama’s Family & Mrs Tudball are characters
Even when Farley (or Sandler or Carrey) started a character sketch, the performers would commandeer the character and just go careening all over the skit
Farrell would do that too, but he also had plenty of characters he just played straight