raph and Mikey still live with splinter and donnie was taken in by big mama and leo was kept by draxum

donnie's tech is a lot more advanced but only because big mama wanted to nurture his interest in it (so she could use it to her advantage)

leo being raised by draxum ended up making him very anxious and quiet ( he's fronting with the quiet part, he wants to be a lot more outgoing and expressive he's just scared draxum won't like it)

uh just the brothers being separated and then meeting each other and coming together again!! leo is a lot more serious and anxious, he has a lot of hope tho