A lot can be unchanged. Most of the older style tech still works, and is just as shoddy as it used to be!
You'll see a little more knowledge about the nitrogen cycle - we used to handle it but didn't have the details on what we were doing. There's a bit of a 'test kit' goggles thing going now, but it's calming down. You have to be aware of chloramines in water, which were not an issue back then. If you pick up a 17th hand version of D=r Innes's old 'exotoc aquarium fishes'. most of it is still valid. Fish names have changed, both scientifically and sometimes commercially/marketing-wise.
There are more fish available in the general hobby overall, but fewer in the chain stores that are taking over. And the health of the fish now is a concern, more than it was.
if you were to visit me, you would see an air driven multi-tank set up, and in that, the tech could be 1960s. LED lights couldn't be, and are an energy saver.