Check whether an account is User or Group - Sharepoint People Picker

I'm working in a sharepoint application. i am using sharepoint PeoplePicker to get ADUser and SPGroup. How can i differentiate the out开发者_开发知识库put from the peoplepicker is an SharepointUser or SharepointGroup

sharepoint site user always have some domain. but for sharepoint site group we dont mention domain of system.like user is"domain-name\abc" while group is "Site Owner, Site Member , site viewer". we add users to sharepoint with domain-name.