Here are the differences:

Different gear sets -- Curado only offers a 7:1 and 5:1 gear ratio in the E series.

Curados have a higher bearing count.

Color schemes are different.

Other than that, they are built on the same frame, new and old. The differences in prices are due to components and the number of bearings in each reel. More info is available at:

fish.shimano.com (no www.)