Pies have gravy (and are pie-shaped), pasties don't have gravy (and they're shaped like a half moon), and a roll is exactly what it sounds like: crust and filling rolled into a cylinder.
And by the way, pastie is not pronounced with a "long A", but a "short A", as in past tense, not glue paste-- which is why when I asked "What's a pay-stee?", the counter gal answered, "What? Oh, a paaahstie... "
FYI, Geelong, a Western suburb of Melbourne, is pronounced "ji' lung" not "gee' long".
Sigh... learning Australian is hard... LOL