An intellectual property licensing agreement is a partnership between an intellectual property rights owner (licensor) and another party who is authorized to use such rights (licensee) in exchange for an agreed payment (fee or royalty).
An intellectual property assignment is an agreement whereby the owner of certain intellectual property rights (i.e. a trademark) transfers ownership of those rights to another person (assignee), where after the assignee becomes the owner (registered or otherwise) of the intellectual property rights.