How can you tell the difference?

[saltwaterkitty]

Can someone please give me a basic rundown on the difference between snowflake clowns and picasso ... and what makes them semi? How you can tell the difference between looking at them?
Thank you!
SWK

 

[florida joe]

check out both fish for sale on this site

 

[btldreef]

http://www.orafarm.com/clownfish.html
The biggest difference is that picasso's are perculas and snowflakes are ocellaris.