Basically, I'm asking if there's a difference between how one plays Dark Heresy and how one plays Rogue Trader and if the classes in both can be combined into the same campaign. If there's a forum like this already, I'm sorry but I couldn't find anything along these lines.

The basic rules are 95% the same, but the level that the Rogue Trader characters start on is a bit higher, and the character creation system for the two games is different.

I would suggest starting your Dark Heresy characters off at +5 to each of their characteristics (on top of what they roll), and start them off with an extra 500xp or so for additional skills. Also, because skills in RT have double the cost of DH skills, the RT characters, in order to level at the same speed as the DH characters, should get roughly double the XP the DH characters get, when you hand out XP at the end of a session.

That, I've found, ends up balancing the characters just right.

Alright, thanks a lot.

in the rt core rule book its says that an dh character thats spent 5000 xp is the same as a new rt character, while this is true the ammount of talents and skill the dh character has at 5k xp dose make them abit stronger.

izak_joule said:

It makes them ridiculously stronger. A DH character with 5k exp could take on a whole party of starting RT characters without breaking a sweat.

There are a few subtle differences between the two beyond the scale and power of each game. You can move and fire while performing a Semi Auto or Full Auto action for example, but you take a penalty to hit rather than a bonus. Damage rolls have a minimum of the DoS that your shot hit by (single shot only I think) and some talents are tweaked in how they work. Bulging Biceps is significantly more useful than the version in Dark Heresy.