Really, they're not. |
Most little girls are way more lumpy than boys, unless they're incredibly skinny to the point of being unhealthy.
Also, most little girls are curvy. This helps make more of an ornament out of the chest, I guess you could say.
By all means, a little girl's chest is almost NEVER the same as a little boy's.
Then of course there's the taboo making it more "riskay" and the fact that you're looking at a GIRL, not a BOY.