Information Systems and Information Technology are often thought of as though they were synonymous, which is a misconception that can result in projects with ill conceived goals that fail to deliver the required business outcomes!
Information Systems is a large umbrella referring to systems designed to codify, gather, create, store, manipulate, and communicate information.
A coding method for uniquely identifying library books.
A protocol and terminology for expressing the quality of a product.
A series of reports providing steering information to a company board.
A method of disseminating board directives to different roles within an organisation structure.
Policies and processes for ensuring that appropriate business intelligence is gathered.
A series of steps needed to provide information to prove a benefit entitlement.
Notice that technology doesn't necessarily feature in any of these. The term 'information system' has been around a lot longer than the computer, or the term information technology.
Information technology falls under the information systems umbrella, but only deals with the technology that enables or supports those systems, where this is applicable. Although the usual examples of information technology refer to electronic communications and computer technologies, a pencil and paper is also a kind of information technology, as are the coloured flags that can be used to send signals between ships. The critical component that turns a paper and pencil into an information system is the method of letters and words that enable meaning to be conveyed.
Indeed, the same information system can often be implemented using different information technologies, and the corollary, the same information technology can be used to enable many different information systems.
There are often skillful aspects of information systems design (e.g. understanding relevant aspects of linguistics, psycho-physiology, sociology) that have very little to do with information technology. Misunderstanding the implications of this when creating systems of information often ends up with inflexible solutions tied to specific technologies, and ultimately to 'technology driven' projects that fail to deliver the needed business outcomes.