Differentiation of self refers to one’s ability to separate one’s own intellectual and emotional functioning from that of the family. At least that’s what wikipedia says when describing Bowen’s theory of family systems.
It has to do with becoming more and more your “self.” Those that have not differentiated themselves and haven’t established an identity outside of their family – tend to need tons of approval and affirmation from others. They tend to conform to others and it seems like they just seem to be full of drama. They tend to be a little insecure of who they are.
Someone that has differentiated themselves tend to be a bit more calm and collected. They don’t really need the approval because they are secure in themselves.
You got friends that are full of drama, always needing approval, and tend to be insecure = low differentiation. Help them to develop their sense of identity and self.