Is there a difference between "Frenchmen" and "French men"?

Solution 1:

"Frenchmen" could refer to French people collectively, including French women. For example:

National Stereotypes in Perspective: Americans in France, Frenchmen in America [1]

It seems that many lower-class Englishmen still harbour a Napoleonic dislike of Frenchmen [2]

It can, of course, also refer to any smaller group of French persons:

Where would you take a couple of Frenchmen [in L.A. area]? [3]

"French men" refers just to men from France (all of them or a specific group, depending on context), but not women. Example:

French men are three times more likely than French women to kill themselves [4]

I think that is the principal difference.

So, in the context of a news article about a couple of people, using "French men" at least makes it clear right away that all of them were men. Using "Frenchmen" would have left that unspecified.

Solution 2:

Frenchman means a person, especially a man, who is French by birth or descent (New Oxford American Dictionary); a French man is a man who is from France.