A patent or patent application for your invention is a property right. Yes, even while your patent application is pending, before the patent issues, you have a property right in your invention.
You can choose to keep the rights to your invention for yourself. Or you can license some or all of the rights to your invention to someone else (typically to a company). Or you can assign the rights to your invention to someone else (again, typically to a company).
A simple way of thinking of licensing versus assigning is to think of real property. Say for example you buy a condo. You have a property right in that condo, just like you have a property right in a patent or patent application for your invention. The right exclude others from making, using, or selling your invention once the patent issues.
Just like you can rent your condo to someone else, you can license your patent or patent application to someone else. The license allows someone else (the “licensee”) to have rights to your invention in exchange for a fee (called a “royalty”), which is typically a percentage of the profits and may be paid to you monthly, quarterly, annually, or on some other basis. Just like the person renting your condo pays you rent.
And just like you can sell your condo to someone else, you can sell your patent application to someone else (by an “assignment”). The assignment transfers rights to your invention to someone else (the “assignee”) for a purchase price (typically a lump sum payment). Just like the person buying your condo pays you to buy your condo. The assignee is then the owner of your patent or patent application.
