Being on the title means that you share ownership of the house. Being on the mortgage means that you share responsibility for the payment of the debt obligation.
In theory, anyone can be added to the title of house - grandparents, minor children, your first cousin twice removed. There's no "qualifying" that goes into being added to the title. To be on the mortgage, on the other hand, you have to go through the typical approval process. Getting your name removed from the mortgage generally requires refinancing (with a couple exceptions, I believe).
