When one party transfers its right on one property to another, it is known as an assignment.
There are two types of assignment, legal and equitable.
If we look at a contract, one party (the assignor) can transfer their right under a contract to a third party (the assignee). The assignor does not need the consent of the other party in the contract as per the express terms and conditions of the contract.
While rights under a contract can be assigned, obligations under the contract cannot be transferred to a third party. Novation is the only method to transfer obligations