I'm not American, nor are Terry Eagleton, David Harvey, Peter Dews, Roy Bhaskar, etc. (And no postmodernist has published a decent intellectual reply to them, I may add.)
There are differences between, say, Methodists and Anglicans, but they are both Christians nonetheless. One may put Derrida, Foucault, Lacan, Lyotard, etc. in the same school of thought, while also recognizing differences. Whether you call that school postmodern or post-structuralist doesn't make much difference when the object of critique is the common traits among them.
Yoshie