I did a little googling, and it looks like "G" is a larger gauge, maybe double size from "O". But looking at that, if it is 23" high then the little lighthouse keeper dude would be about 5/8 to 3/4 or so tall... which seems about right for "O"... but maybe I'm wrong...
ecurbh remembers it said O gauge on the package. and it looked to scale with the other o guage buildings they had, like a depot and stuff.