Personality evolves over time as you get more experience, allowing for equipping of PlayStyles that were not accessible before and potentially losing access to those associated with a Personality type that no longer represents you. There are also generic PlayStyles that can be equipped across all the Personality types.
When you progress to the last level of Personality, if one of the Personality types may become highly dominant, you will get access to turn one of your equipped PlayStyles into a powerful, more refined version called a PlayStyle+.