Drawn vs. Photographed

Sorting between drawn images and photographs reveals a pretty solid split. Interestingly, the categories themselves split into creator and curator sub-categories. 

Curators with a drawn image are usually blogs dedicated to fandom. They also usually do not create their avatar image themselves, instead using screencaps or other fanart.

Creators with a drawn image are always blogs run by artists who mostly create their own content. While some are self-depictions, not all are. Their avatars are usually a quick look at their style/usual depicted subjects.

Curators with a photo image usually either depict themselves casually or choose a photo of something they enjoy. Their content varies between fandom, personal reflection, and photography/art/specific aesthetic themes.

Creators with a photo image usually depict themselves or their work in serious or formal settings. They also surprisingly tend towards black and white images. Their avatars are generally a bit less indicative of their content than artists who have drawn their own icons.