Assignment of copyright and copyright license are two forms of contract involved in the exploitation of copyright work by a third party. Each has its own distinct characteristics.
A license is an authorization of an act without which authorization would be an infringement. Licensing usually involves licensing of some of the rights and not the whole. Licenses can be exclusive or non-exclusive WHEREAS An assignment involves the disposal of the copyright: the author (assignor) assigns the copyright to another person (assignee) or transfers ownership of the copyright.
However, In the case of license only specified interest in IP is transferred not the ownership is transferred to the licensee.
A license normally does not confer any right to licensee against licensor or third party but exclusive licensee has substantial rights against the licensor, even to sue the licensor. And by Section 30 if the licensee in the case of future work dies before the work comes into existence his legal representatives shall be entitled to such works, in the absence of any provision to the contrary.
A licensee has a right to make alterations except in so far as his license expressly or impliedly restricts the right. A failure to pay royalties enables the licensor to revoke the license whereas in the case of assignment it is not possible. But if there is any harsh terms that affect the author can lead to revocation if a complaint is made to the copyright Board.
The expression “assignee” as respects the assignment of the copyright in any future work includes the legal representatives of the assignee, if the assignee dies before the work comes into existence.
The owner of the copyright has the power to assign his entire rights or assign only some of the rights. In case the rights are split up there is only partial assignment. Assignee will be the owner of the copyright as regard rights so assigned, the owner will be the owner of the copyright of the remaining rights. The assignment could be for the whole duration of the copyright or for a short duration