Standing side by side is a re-issue 7-11 Eddy Merckx frameset and an Original version. If you can not tell, the one of the left is original which is constructed of Columbus TSX, and the re-issue on the right is designed out of Columbus SLX. The main difference is in the forks, the original uses a slopping fork and the retro has a flat crown. Via John Prolly.
Edit: The one on the left actually the re-issue, Thanks John!