Brine shrimp eggs normally have a shell, or capsule on the outside, so you can't feed then directly to fish, as the shell isn't edible. That means you have to hatch the eggs out, in salty water, and then separate the shrimp from the shell.
It takes about three days for them to hatch, so you have to know that you have eggs and get the shrimps hatching ASAP, or you won't have food ready by the time the fry become free swimming, and they could possibly starve.
Decapsulated brine shrimp eggs have had the shell removed, so they don't need to be hatched (in fact, the ones I have are a sort that won't hatch anyway), so you can feed them to fry just as they are.
They're not quite as nutritious as baby brine shrimp, but are nearly as good.