Are modern Amish much more dissimilar from society than the original generations of Amish?

I read that the Amish trace their roots back to the late 1600's. It seems to me that their culture is vastly different than the mainstream, in part because of mostly (but not entirely) rejecting modern technology. Also modern fashion, music, etc. However would I be correct to think that in the late 1600's and early 1700's such differences must've been much less pronounced? I mean, I imagine that the level of technology and the fashions, etc which modern Amish have are approximately the same as what most people in the colonial times had? It's not like they are always lagging their technology 200 or 300 years behind whatever is current, and were thus using 1300's tech in the 1600's, right? When did they decide to freeze their lifestyle? Was that always a part of being Amish or did it come later?