Back in the day ("when I was young, I'm not a kid anymore...") before everyone and their brother had cell phones, teenagers longed for a way to communicate with each other in a way that would elude the parental units. So we did what any "rational" person would do, we bought pagers. What developed could probably be considered a precursor to texting.
A GLOG is a Graphic-Blog. At glogster.com you can create visual posters. Glogging becomes a way to write using pictures, text, graphics, and multi-media.
A VLOG is a visual blog. Instead of doing our daily writing in a journal, we created mini-vlogs to let others know what was on our minds.