Music: Commonalities

Here's a headscratcher from Eric (who successfully solved Thursday's Cryptogram, by the way).

What do these bands have in common?

• Aerosmith
  
• Elton John
  
• Earth, Wind, & Fire
  
• Joe Cocker
  
• Cheap Trick
  

Conversely, what do these bands have in common?

• Chuck Berry
  
• Carl Perkins
  
• The Marvelettes
  
• The Isley Brothers