tristanguigue

Someone already answered about the price, regarding the success rate, there is a much bigger difference than this:

Space X has had 29 launches, 2 failures and 1 partial failure (F9-004) so a success rate of 89.6%.

Ariane on the other hand hasn't had a single failure or partial failure since 2002 so if you compare since Space X started its services it has a success rate of 100%. If you take the whole history of Ariane it has indeed a success rate of 95.2% or 95.4% for the Ariane 5 version but the fact that Ariane has flown 72 consecutive missions without failure (2002 - Present) compared to 14 for Space X (2012 - 2015) says a lot about their reliability.