If you have not already made the leap, there is no reason not to update. Especially now that most of the eager beavers hitting the servers have finished and our requests and validations will happen quickly.
Read Apple's page Update to iOS 14 or iPadOS14 - Here's What You Need To Do before you start down this path.
Widgets on the iPhone are the biggest change for me. I have changed the Home Screen view to show the App Library (you know how many apps I have and rarely use). But App Library does not seem to be a feature in iPadOS14.
Read the iPad online User Guide or iPhone online User Guide. Also remember to download the Books iPhone User Guide for offline reading.
Mark your calendars for November 5th and 12th to share your discoveries with iOS14 and iPadOS14. "Same time, same Bat Channel."