In a lot of cases, the CSUs are much cheaper than their counterpart, the UC system.
However, CSU is in such a way that admission is much easier while UCs are tougher to be able to enter.
The two also have their own different approaches. The CSU is more focused on their professors to teach the material to their students, while the UC prefers to do lots of research, such as the Lawrence Livermore Lab.
Lastly, if you are considering to go to a community college and having a choice to transfer to a CSU or UC, a CSU is a better choice because the list of courses you need to take for your first two years of GEs are much easier than a UC.