>>21265522Here, here are both versions of their overworlds from HGSS. As you can see the size difference is pretty substantial, even with their following overworlds being some of the largest ones.
For following overworlds, here's the general size reference from the OW guide on the wiki: Smaller mons are usually from 16x16 to 24x24, larger mons start around 24x24, at most 32x32, the biggest (non giant) mons and medium-sized legendaries are usually around 32x32, the giants such as Wailord and Steelix are usually only a bit bigger (say 2-8 pixels), HUGE legendaries can be up to 48x48 (this girth is not to be used lightly).