I'm a fan of Ra. Have been for a long time. I've introduced it to many people over the years and have had fairly positive responses to it, though not universally positive. Ra has some great pieces to it and really has a nice look. However, many still have a hard time grasping it right out of the gate.

With Razzia, we haven't had this problem and I also find that players I expose to Razzia first, prefer it to Ra.

The biggest three differences in the game are significant. First, explaining Razzia is a lot easier. The collection cards that are discarded each round are marked with large X's on them making it very clear which ones stay and which ones go each round.

Second, the lack of disaster tiles gets everyone up-to-speed much more quickly and it really doesn't take anything away from the game. Having them in Ra just changes the flavor a bit. Not having them still retains the same feeling and balance.

The third factor is the theme. The theme in Razzia is, I believe, a more graspable one. Instead of compiling "Pharoah's" you grow the size of your mob. This makes sense. The other cards are pretty well themed too.

I'm not going to be giving up Ra but I think Razzia stands a much better chance of getting to the table more often.

If you've never owned either and are interested, start here with the cheaper Razzia and you'll likely end up with a better value to boot.