I can elaborate on the differences.
Sound is night and day better very crisp and much more throaty/aggressive. I really like it in all modes plus ability to put it in quite mode when towing.
Suspension night and day better, it’s way softer on the small stuff but handles better and takes big hits much better plus puts the power to the ground much much better.
Engine/transmission like it was totally redesigned. Lag is almost non existent with way more power through the rev range, much smoother and fluid feeling, the transmission is night and day so much smoother and smarter its hard to explain but again it’s like it was completely redesigned.
Interior is obviously way nicer with much better displays and features not even a comparison.
Headlights are a huge improvement and a pleasant surprise.
Appearance is personal, I like the new design as much or more but it definitely wasn’t a driving factor for me. They both look awesome.
Having owned a 2018 for 1 year and a 2019 for 2.5 years I feel very qualified to give this comparison. The 2018 I felt rode much better then the 2019 but felt sloppy and tippy in turns, the tranny logic was awful. The 2019 handled better but was very rough over small to medium bumps and terrible on bumpy dirt roads as far as the back end kicking out, the transmission logic was better but still not spot on. In my opinion, the 2021 has been under promised and over delivered, it perfected basically everything that annoyed me in the G2 2018 and 2019. All of them have been 801A trucks.