Plaxo/Linkedin vs Facebook/MySpace

Basically these sites all provide similar services, but simply said I think it's the professional business type vs the average everyday person. I know, I know that sounds like to simplistic point of view, but as I have explored these sites that theme seems to be apparent to me. I view many aspects of business-minded applications in Plaxo/Linkedin and non business related applications on a more general community-minded applications at Facebook/MySpace.