I was playing with my childhood set of Legos yesterday (ya I'm cool like that) and made an interesting observation. I quickly noticed an alien amongst my pristine collect, Megablocks (MB), blasphemy! I'm not sure when my little Brother or Mom bought the set but they creeped their way inside the huge Rubbermaid container. Like most rip-off products the differences are very small, however the subject matter is so basic those tiny differences make a huge impact. While ousting the impostures I noticed how quickly I could pick them out among the crowd. In fact, it was easier to spot the MB than the Lego pieces I was searching for...
The Lego edges are crisper than MB. The radius on the sides do not appear larger but the edges still seem sharper. I think this has something to do with another issue which brings me to my next point, material.
The material of MB is slightly translucent and thus appears lighter. At first I thought the color was less saturated but when I held the yellow block into the sun I saw it was translucent . The lighter color leads to less contrast particularlly when comparing the yellow blocks above. Less contrast also dulls the edges which makes them appear less crisp than Lego.
If I remember correctly from a How It's Made episode, Lego's are manufactured with no draft, which is pretty incredible (Sorry there's no link I could find online. However, here's a link to a video produced by Lego from the 70's before the time when computer did everything. Just watching their designers working on a drafting table gives me a headache.) The gray MB piece has a sink mark on the gray piece and I even saw a few ejector pin defects, ouch.
So when you add all this up it seem pretty clear why Lego is a superior product. No wonder I could pick them out so easily.