circumcision

I live in the UK and can honestly say that I don't know anyone who is circumcised but having seen comments on glow I understand that most baby boys in the US have this done (please correct me if I'm wrong). i understand that this may be performed for religious reasons but many people have given hygine as a reason (i have never heard this before or know of anyone who has had issues with it).There is a big push in the UK to stop fgm and what I wanted to know is why is it acceptable to circumsise when fgm is illegal. I don't want to offend anyone I'm just interested in explanations for how it is different as both are procedures performed because of beliefs.