A course at the intersection… 

— Interaction design is the creation of a dialogue between a person and a product, service or system.
— Information design is concerned with making complex information easier to understand and to use.
— Information visualization is graphical representation of (quantitative) data or (qualitative) concepts. Also known as information graphics. Often used to tell a story.
— Data visualization is very similar to information visualization, but more purely about representing, and allowing the exploration of, numbers — quantitative data. Often lets the user find her own story.

When these come together is where it gets interesting.