Yeshivish lite (Chassidish lite, tuna beigel) refers to someone who holds onto the ideology and the social norms of the community as best as possible, while bending either due to weakness or a mistaken feeling that he needs to bend to get ahead begashmius. Much of the bending has to do with external appearance, and many of those who bend later snap back or at least hope their children snap back.
A bum or an oisvorf is another story altogether – these unfortunates don’t believe and don’t want to keep the mitzvos or even lead productive lives, but they want to retain the benefits of community membership along with a certain superior attitude (really fear and a deep inferiority complex) that makes them want to rub their OTD status into everyone’s faces and take others down with them. These unfortunates need help, but really they can’t get help without being removed from our dalet amois so they do not continue to create a destructive subculture within our world. (Not all OTD are bums and oisvorfen either.)