As an answer to how T9A's Saurian Ancients play differently from Warhammer's Lizardmen:
There's a lot in common. For those who played a primarily guerilla-war strategy, with small units of Skinks and other fast shooters running all over the table, it's changed significantly. That approach is massively restricted. For those who play a combined-arms kind of list, with some basic Core backed up by a range of support units, all supported by a hefty Magic Phase, there are definitely changes to learn to the game as a whole, but you still basically bring a few good combat units, a serious wizard of some kind, lots of small stuff to run interference and dictate movement, and some powerful support units to help clean up when things get up-close and personal.
If you were comparing T9A to Lizardmen from back in the day - that is, 6th Edition up through the earliest days of 8th Edition, I'd say they've radically changed because Saurus just aren't the dependable, resilient bricks they once were. But that's not different from where 8th Edition ended up.