There are Black Belts...and then There are Black Belts
I get amazed at how many people ask what does it mean to be a black belt? Does it mean you are good? Does it mean you can teach? Does it mean you can make me a lethal weapon? Does it mean you can train me to be in the UFC?
At the end of the day, the real question is: Can an instructor walk you down the path you want to go and help you learn what you want to learn? Does it matter who he is certified under or where he learned it? What matters is can you get value out of the lessons, are they what you are seeking and what you want to learn.
We've all been through the educational system and had experience with good teachers and bad teachers. I went through University and earned A+ marks in all my statistics courses with the same teacher for 4 years.
One year, I took a course with a different instructor and failed it. The guys was smart, but a moron teacher. The next semester, I took it again with the good teacher, and got an A (sorry, not an A+). Was I stupid? Was I unable to learn? Clearly the answer and the evidence says no. But when you can find a teacher who you can identify with and respect, the learning is exponential and the ability to learn is amplified.
If you want to be the forms expert, then Karate or traditional martial arts is good for you. If you want to be the most fit guy in the world, then Crossfit is for you. If you want to learn how to survive a stand up fight, Muay Thai could be for you. If you want to learn how to fight on the ground, then Submission Grappling or BJJ could be for you. If you want to learn all those ranges, then MMA may be for you.
So many other questions come to mind, such as do you want to push your physicality? Push your mental ability? Do you just want something to do 3 nights a week? Do you want to find your limits and exceed them? The list goes on and on.
At the end of the day, figure out what you want to do, and find an instructor who can help you with those goals and provide you the right environment and the right motivation. Clearly I am assuming they have the skills to get you there.
Don't go to a Karate school and expect to learn self defense. Don't go to a Muay Thai club and expect to end all fights standing up. Don't go to an MMA club and expect to learn how to defend yourself against a knife or multiple attackers. Have some kind of realistic expectation to what can actually be provided by the place you are going to.
So the answer to the question are there different black belts? The answer is yes. As many different types of belts as there are styles. Find the one that matches your outlooks and goals, enjoy the ride and train on!