It also seems like his hair changed from the first to the last episode.
It seemed to have a patch of blonde hair on top like the sun-bleached it, but by the end of the first season, the blonde hair was gone.

When i look at the early season 2 episodes, it looked like he grew a lot over the year since the beginning of the show.

Awww shucks - they grow up so fast !

lol his hair is quite different over that period - starts out kinda tight wavy (a bit of a curl) and then later becomes more flowing

seems like Beaver's later maturity hardly reaches the level of young Wally (?) by design ?