I just found this post while looking for other icon info. The master list of icons is found on the Instructure.design web site. There is a wealth of info there. Is seems to be mostly for developers, but there is some good info for designers, if you dive in to html.
@evangelinadlf , I'm not sure if there's a master list somewhere, but here's a list to the bulk of them -
How do I use the icons and colors in the Gradebook? and then this one includes the difference between quizzes, assignments, and discussions - https://community.canvaslms.com/docs/DOC-10092-415254365
Hope this is helpful! Kona