He's talking about how his relationship with Jay-Z is more like them being brothers. Of course with them like brothers there are the ups and downs, like sibling rivalry, competing for love(of the listeners), seeing who is better, the little brother wanting to either surpass Jay-Z, or being forced into his shadow ("have you ever walked in the footprints of a giant"). Then, Jay-Z has also shaped his career and in many ways forced made Kanye think outside the box thus making his better.