Some upgrades, some downgrades.
The glass broke oddly in s2. It could literally hang in the air with no connection to anything.
The bottles in the bucket wasn't down there but on top like it was an solid object. When he picked it up they just flew right off. That's probably the models fault though since the box with balls moving were more accurate.
While the grass was an update,it looked weird that it reacts to your hands but not when a brick gets dropped on it.
When he tries to toss the TV through the window the second time it doesn't change the way its been damaged, making it look like it was ghosting through it when it didn't affect the shatter at all.
While being upgraded, we are comparing engines that are separated by two decades in between them.
Compared to that then the jump doesn't feel that big.
I was more impressed by the details of textures which also shows how old hl2 is.