I had a similar problem with my sister when I was younger. The way I solved it was by doing something that was unique to me and only for me, that set me apart from her. It happened somewhat by accident, but I traveled to a foreign country to study for three months, somewhere she had never been. I returned a completely different person... I felt unique, I had a personal identity apart from her, and I had great stories to tell. Suddenly, people were listening to ME and I was no longer under her shadow.

A book that is more so on careers, What Color is Your Parachute, may be helpful... or perhaps the Myers Briggs personality test and book would be helpful -- I think this test can be found for free online. But really, it comes down to YOU discovering who YOU are through some self-exploratory means.... perhaps journaling it... what are YOUR interests, YOUR goals, and YOUR passions in life.. what do YOU want to pursue in life.. what are you good at, what are you best at, what comes naturally to you.... you can write all of this down as you're thinking it through. Perhaps set a goal for yourself.... and then pursue it. Achieve something that is all your own and apart from your brother. Once you start to focus more on yourself and not on your brother's accomplishments, you will start to feel better and more unique.... you ARE unique and have special gifts in this life that only you own, and not him and not anyone else. The key is to discover what those gifts are, and it can be an exciting, exhilarating experience of self discovery.