Just for the records: Myriad (Pro) is a licensed font and not allowed to be embedded with CSS in such a way that the source files can be downloaded (and they can if you upload them to the server and reference them in the stylesheet).
Now, as to the differences: I don’t know if and how this still applies but I remember Webkit browsers using PostScript font names while others use the normal names. Also
http://rachaelmoore.name/posts/desig...-family-stack/ might be an interesting read.