I am a Scholar of Star Wars. That means I know just about everything about it. Knowledge of Star Wars is the only thing I claim to be an expert of.
I am a Student of Film and Television, Linguistics and Drama. This means I've studied them at length in at University. I don't claim to be an expert but I do know more than the average Joe.
I am a Professional Software Developer. This means it is my job to design, write and implement software. As such I have a pretty good idea of how software companies work, though again I'm not an expert.
I hope that clears up what I am and am not an expert of.