Hi and welcome to the forum.Yes they are entirely different bikes and having had a Dakar 650GS, 1150GS and now a 1200GS and loved them all in different ways, I would never go back to a 650GS, but that is only my personal opinion.If you are intending to use them like a dirt bike, remember they are very heavy and you will not be able to go where a trail bike does, so they are suitable for gravel and easy dirt roads only, unless you have very good off road skills.My advice to you would be to try both of them out for a day or so if your dealer will allow you.The 1200GS is an extremely easy and capable road bike to ride and will eat up the Km's also as many sport bike riders have found out it has great handling in the twisties.Have fun ChoosingRegardsJim