The BMW X1 and X3 are both luxury SUVs offered by BMW, but they have some key differences in terms of size, performance, and features. The BMW X3 is larger than the X1, it has a longer wheelbase and overall length, which results in more interior space. Also, the BMW X3 has a more powerful engine lineup than the X1. However, the BMW X1 is a less expensive option for those who prioritise efficiency and agile handling.