If you're satisfied with it, you don't need to update. But Openboard lacks a lot of features many people want. The biggest of them is probably the glide typing, which Heliboard supports. And it also added a lot of quality of life improvements.
Some new features, bug fixes, and ongoing support.
It is a new application so you do have to set it up fresh - don't switch until you have a bit of spare time. Missed the back and restore button in settings.
Personally I'm on one of the fork's beta versions. I'm waiting for the f-droid release so I get updates.