Try here http://www.pcgs.com/News/1909-Matte-Proof-New-Coin-Die-Discovered Unfortunately the photos that Charmy posted of the diagnostics I can't help you with.
I'm guessing this thread was revived because of the coin in question on this thread: https://www.cointalk.com/threads/ebay-still-a-cherrypickers-paradise-2017.290909/ Or this one maybe... https://www.cointalk.com/threads/1909-vdb-matte-proof.286197/ ???
The difference is one is a 1909, which used 3 obverse dies while the other is a 1909 VDB, which used 1 completely different obverse die.