There are many types of Hmong. There is the White Hmong, Green Hmong, and Stripe. (There are other types of Hmong also, but I don't recall them at the moment.) The difference between them is the way they dress. This is how the Hmong Green ladies would dress:

The Hmong White ladies:

The Striped Hmong Ladies:

As you can see, you can tell the difference from what each culture wears.