
I believe the grammar and vocabulary is a bit different, but to what extent I don't know. Also, the phonology is a bit simplified in Western Armenian.
If you're looking at East Armenian you'll find to writing systems in use. The Reformed spelling in use in Armenia (which is what most modern resources use to teach you) and the traditional spelling in use by some of the diaspora communities and in use by the Western Armenians. ( At least I think that's right
