What's the difference?

What's the difference between the right to an abortion and the right to circumcision?
Recently a couple towns in California voted on bills which would outlaw circumcision. These bills didn't go too far, in fact in Santa Monica the bill's sponsor regretted her action once she learned how far it would go in curtailing rights now claimed by both religious and secular people. Anyway, most people opposed limits on circumcision, believing it a personal decision (although one generally imposed on very young babies). 
Many of these same people would probably NOT oppose limits on abortion. And I wonder why? Although some might say that's it's a life on one hand and a relatively minor procedure on the other, others would disagree.