It depends on the type of interaction, if it is a "formal" quick conversation with a stranger I think girls are a bit easier to talk to. Less aggressive, generally more helpful if you ask for information etc... But on the other hand of those few real friends that I had in my life, none was ever a girl.
I can't get close to them, for example if I am in a group of people and some or even most are girls, it's (more or less) fine, but if I happen to find myself alone in the company of a girl then I immediately get this feeling of complete inadequacy to the situation, regardless of circumstances. I guess as soon as I'm alone with them I find I cannot "play a part" any more, and she will inevitably figure what kind of strange weird person I am.