They seem about the same size to me. Some are large and some smaller.
EQII will download enough of the game for you to get character select, and then download the starting areas for the new character. It then downloads the rest while you get up a few levels.
EQ you have to download the entire game before playing.
"I think I lost my harmonica in House of Thule." Geroblue
'Through the thorns to the stars', Ghost in the Shell