Thanks to my cousin, Eric, I have both French pajamas and American pajamas. Let me tell you about the difference. American pajamas have zipppers -- at least the kind with built in feets which my folks seem to favor, I think they're worried about me getting cold -- and French pajamas of the same ilk have snaps: lots and lots of snaps.
Take these for example:

French Red Striped Pirate Pajamas. They have snaps up the back, between the legs and across the tooshie. They really are a test of Mom and Dad's snapmanship (or snappersonship if you prefer.) I have a similar number from the Gap I like to call Robot Parade. One zip and I'm ready for stories and bed. The snap under the chin is totally optional. And yet? I prefer the French Red Striped Pirate Pajamas. Come on! They're French! And they have a pirate!
P.S. Props to Aunt Poosers for the pics. She delivers!