Complex vector illustrations with multiple artboards or embedded images open up to 2x faster than in previous versions.
There is no difference. The 2020 version of Illustrator simply dropped the 'CC' from the name. It's happened across the board. Vector Graphics Software | Adobe Illustrator Adobe illustrator 2020 24.0.1.341 Multilingual
Please note that this list of features is not exhaustive, and Adobe Illustrator 2020 may have many more features and capabilities not mentioned here. Adobe illustrator 2020 24.0.1.341 Multilingual