I'm not sure what you mean?
I have a fair amount of Lock n Lock......as well as a couple of glass sets. There are a couple of different lid styles, although all of them have the flaps on all 4 sides that you have to latch on to the tabs on the base.
The difference, I think, is whether the lid is somewhat domed or is simply flat. In this TSV set I posted above, it looks like there's a mixture of both types, although the domed types usually have a handle. That said, I have flat lids with handles, so I don't know if that's why it's sort of domed.
The quality of the plastic lids in the glass and plastic sets I have is exactly the same.
The only Lock N Lock I have that I have NOT been happy with is a set I got made out of Tritan. I think it was a 6 container set, and the larger ones (the ones I really bought it for) lasted once - the tabs broke off. Interestingly, in the set I bought, it received a lot of bad reviews for this same reason.....there were no reviews when I bought it, but tons of positive reviews on other Lock n Lock tritan sets, so I didn't worry about it. I think it must have been a fluke set with an issue. Out of all the sets I've bought - and unfortunately, I've way too many, this was the only bad set I've ever purchased.
Does this help?