Mr. Orange's rank represents the level and ability his previous dojo gives to "orange". That's it. What "orange" means in your school is obviously different. Your sensei may recognize his "orange" rank, but I'm sure Mr. Orange will have to meet your sensei's qualifications for the next rank. So don't worry about it.
With that said, rank only tells you where you generally are in your particular dojo. I was ranked 5th kyu at my old dojo. When I changed schools, I realized that I was not really at a 5th kyu level at my new school. So, I decided to just start over from the beginning. I was only 5th kyu at my old school not my new one. Three years later, I'm really glad I did start over. All the people I used to train with at my old school are now "black belts." Well, they are the level of black belts for that organziation. If I stuck around, I would be a black belt, too. Yet at my present school, I'm gladly and proudly a 3rd kyu and still have a very long way to go before I'm a black belt. There is just so much more to learn where I'm at now.
Everything is relative. Even ranks from dojo to dojo are relative. I use it to give myself a measure as where and what I need to work on and learn to be better. Outside of that, even comparing my rank to others in the school, rank is useless.