Thanks is a new feature that was introduced a few weeks ago... I'm not *actually* sure what the point of both are - I think it's just a nice way to say 'Thank you' if someone is useful. Reputation is more when someone almost goes out of their way to inspire another individual, so I guess maybe it's a more significant marker? And perhaps the 'Thanks' adds to Reputation power... ...thinking about it, there's probably a thread somewhere from the Administrator of the board explaining it all...