There are some basic and important differences between you when it comes to how you live your lives. Your senses of individuality will be directly in conflict. Your friendship could become a confusing push-pull between togetherness and individuality.
You'll share a strong bond, but you'll be trying to preserve that bond while your buddy fights it, viewing it as a threat to their individuality. This could come in the form of arguments over all the things in life that are most important to you -- your interests, your values, your politics and more. You'll have a hard time laughing about your differences, and through arguing your own point of view, each of you will be subtly trying to dominate the other in ways that could lead to some major clashes. This is a very unstable and difficult aspect to deal with in a friendship, and it will take plenty of patience on both your parts if you want to keep getting along.