You know how mothers of identical twins can always tell them apart. Well, "good" chicken owners always know exactly which hen laid the egg. Haha - NOT. Don't worry, you're not alone.
Over time, I have come to recognize the eggs of some of my hens by size, shape, spots, hue/color etc, but by no means all of them. I spend a lot of time at the coop and if I see a hen in the nest box and check back an hour later and there is an egg there, then I think "Aha, now I know which one lays that roundish egg". I do have one that lays a roundish egg, one that lays an egg with pale purplish speckles on it, a BSL in her third year of laying who lays a ginormous egg, a white egg layer, a green egg layer and a marans. So I can tell those eggs apart. But the rest.....to some extent, still a mystery.