Not clear to me either. It looks so similar to the page in the FR Campaign Setting book that was made for level adjustments that I assume that it means the same thing here. However, nothing positive to go on for that assumption.
Anyone care to take some guesses as to what each creature depicted is? I think I see a half-ogre, a bugbear, and a half-dragon there...perhaps a kobold as well.
I'd guess you are dead on, because I can make out a bugbear, an ogre, a half-dragon, and a tiefling, each holding their correct respective level adjustments...
If it is indeed an ECL chart, there shouldn't be any kobolds listed. So, it's gotta be (L to R) Aasimar, Bugbear, ?? (looks like a vampire but ECL is waaay to low), drow (the iconic Maddie Webber from the Urban Arcana cover - ugh ), rakshasa?? (what's the ECL?), half-dragon, ogre, tiefling.
I think the "catman" may be an anthropomorphic lion. The ECL would be right for it, anyway. Not sure about the gaunt guy, or the scrawny red +2 devil thing.
Okay, my best guess, from left to right:
Aasimar, Bugbear Mobster, Elf or Changeling, Drow, Gnoll Gangmember, Half-Dragon (Red), Ogre Rastafari and Tiefling.