The page lists the following two features as being unique to the HTML5 version which I believe were not yet public knowledge:
- GameMaker Team collaboration feature
- GameMakerBlog in Top Ten of Top Gaming Blogs to Follow in 2018
- GameMaker Studio 2 Winter Sale brings warm savings to developers
- [Giveaway] Deios 2 Steam Key Holiday Giveaway
- GameMakerBlog Levels up with new IndieDevHelp initiative
- [Indie Interview] uZombie made in GameMaker!