Assignment
The act of unilaterally passing your rights, but not your obligations, to some other fellow.
As a matter of contract law, one can assign one’s rights without one’s counterparty’s consent (broadly speaking, why should she care?), unless your contract states that you cannot, in which case you cannot.
You cannot assign your obligations to anyone without the counterparty's consent. This stands to reason, since another chap might not be as skillful, creditworthy or personally attractive as you. Therefore your counterparty must consent, and if he does, it is called a novation.