Capable is more of a mentality. Able is more of a physical idea. You can be mentally capable of describing the object in front of you; you can be able to lift the 100 lb weights. However, the words are nearly interchangeable anywhere. Even in the examples I gave, the other fits, but one seems more appropriate than the other commonly.

Difference in "capable" and "able"
I'm looking for the "Rannoch: Admiral Koris" mission. Who or what do I need to interact with to receive this mission? I know it's possible to permanently miss certain missions by not accessing them before completing other missions. Is this the case with "Rannoch: Admiral Koris", or am I just not wandering around in the right places?
