What are the major differences that one would notice between a Sephardic and an Ashkenazic wedding?
A few that come to mind. By the Sefardic wedding the Chasan makes a Shehechiyanu and puts on a new Talis under the Chupa, which is not done by the Ashkenazim. By the Sefardic wedding the Chasan leaves the Chupa and goes to greet the Kalla as she is coming down the aisle, which is not done by the Ashkenazim.
Sephardim don't have a cheder yichud. In Israel, they swear under the chupa not to marry another woman (while still married).