I was reading a book recently and it equated brand with reputation. My first thought was "aha", that brand is just a fancier/newer word for reputation and why I hadn't I matched those two up before? But as I thought about it a little more, I'm not sure the two are the same. I think of brands as the very public face we project, the one that gets our foot in the door or that causes people to contact us with work, where reputation is something that's determined by what you do rather than what you say you'll do.
I think that's an important distinction because building a brand can often just be cosmetics. Yes, it takes some work, but there are ways to short cut that and even if you don't, that brand may not accurately reflect who you are - it could be who you want to be, or who you think I want you to be.
Reputation is something you earn by being who you are. You can be nice, or not, hard working or not, reliable or not, fun to work with, or not. You can try to earn a reputation for being whatever, but you don't get to decide what your reputation is. Of course that doesn't mean you can't work on your bad habits or your rough edges to make your reputation stronger.