In my experience, Juggernaut plays more like a typical warrior, while Marauder plays more like a rogue (in both cases I'm comparing to WoW, AoC, etc)
The only things that differs a marauder from the image of a rogue would be the lack of stealth, however many things are very similar in that you use medium armor, dual wield, have a TONNE of defensive cooldowns and are very capable in pvp 1v1 or 1v2. Heck, we even have a short vanish.
Juggernaut on the other hand fits the warrior title well. Tanking feels right, aside from the slightly higher difficulty on aoe pulls. In pvp they are quite solid as well, proving to be one of the best ball carriers with damage reduction cooldowns and charge.
Having leveled both myself to 40+, one thing I would suggest is going darkside on one, and lightside on the other; it at least provides dialogue changes in many cases.