One source for cloud documents

The difference between storing things as CC documents or in the 'Document Cloud' is not apparent. It's actually really confusing.

I accidentally saved an XD file as a 'Cloud Document' and it took me a while to figure out where it was actually saved so I could remove it. When I logged in on the website, under Web Apps & Services I assumed the file was in the Document Cloud – thinking the word were just reverse but the concept was the same. Later found out I had to go to Creative Cloud.

I am still not sure what the difference is or how I can save things to the Document Cloud. Shouldn't there just be one cloud storage area?