Whilst the IP Assignment Agreement usually addresses the assignment of pre-incorporation IP rights to the startup, an Invention Assignment Agreement assigns the rights that may arise during the lifetime of the startup, it is usually drafted in a “futuristic” manner such that it assigns to the company, rights that may arise whilst executing tasks in the ordinary course of business.
Parties to sign an Invention Assignment Agreement would usually include employees, founders and/or consultants.
It is not unusual to have the IP & Invention Assignment Agreements subsumed under one document.