Okay, this is entirely my opinion.
This is how I felt towards the transition between season 3 and season 4 of rebels.

.Ezra S2 - he was cute, sarcastic, slightly silly, and snazzy.

.Ezra S3 - he has turned mature, hot/adorable, serious, modest, protective and very brave.

.Kanan S2 - He was cheeky, funny, and definitely low on patience.

.Kanan S3- He became more serious, lost his cheeky behaviour, became more protective.

.Hera S2 - she was reckless and understanding.

.Hera S3 - she was more serious, skilled and more of a role model for Ezra.

.Sabine S2 - rebellious, protective, and snazzy.

.Sabine S3 - loyal, mature, and got new skills in art. 

.Zeb S2 - always ready for a fight, kind, rebellious

.Zeb S3 - loyal, protective, and more of a brother towards Ezra.

.Chopper S2 - sensitive, disobedient, trouble maker.

.Chopper S3 - more loyal to everyone especially Ezra.