You can see that some them are closely related when they have the same first Latin or Scientific name.
All of these butterflies are in the Brush-footed family.
Empress Leilia - Asterocampa leilia
American Lady - Vanessa virginiensis
Red Admiral - Vanessa atalanta
White Admiral - Limenitis arthemis arthemis
Red-spotted Purple - Limenitis arthemis astyanax
Viceroy - Limenitis achippus
The references and gear I used for this blog are:
Camera: Canon EOS 40D
Lens: Canon EF100-400mm F4.5-5.6L IS USM
Camera: Canon EOS 10D
Lens: Canon EF28-105mm F/3.5-4.5 II USM
Steiner 10x42 Predator Binoculars
Kaufman Focus Guides - Butterflies
Butterflies through Binoculars The East
Butterflies through Binoculars The West
Butterflies of the Great Lakes