Definition: Interactive Design
My definition of interactive design is the notion of physically/mentally taking part in the act of whether your communicating to someone, how you approach nature, processing information whether buying a product or reading information online and how you interact with it.
Definition: Informational/Instructional design
My definition of informational/instructional design is the role of gathering information from several, preferably accurate sources to then put them into play by presenting them in a clear state where the user is able to easily follow the information.
Joel's Development Design Experience 