Eh, I think the biggest change is that technic style bricks are pushed down much farther in the line than they used to be (late 70's early 80's). There are a lo

Eh, I think the biggest change is that technic style bricks are pushed down much farther in the line than they used to be (late 70's early 80's). There are a lot more moving parts, more wheel and tire styles, and the average part is now a 1x or flat rather than a full height 2x4. There's also just a lot more sets and options. The other big change is that all of the sets have instructions that the kids seem to start out following, and some of that comes from the branding, but some also comes from the more complicated nature of the more technic style sets. There are a couple of unique parts per set, but nowhere near what most pundits claim. Most of the parts are interchangable for builds, especially if you're not too worried about the colors. (source, 3 kids now in their teens with 10+ years of someone getting at least one set for christmas/birthday, and 1/3 m^3 of lego that's less and less used now. And my own collection of ~ 1/2 ft^3 from way back when)