Hey @ZZZ0mbieSSS!
With every new release, there comes engine improvements and new features. This allows the release of new major features and changes without forcing everyone to upgrade all at once, which could negatively impact some projects, and version control just in case there are features you don’t need, bugs, incompatibilities with your code, etc. Here is a list of new features introduced in 5.1:
I hope this helps your decision!