What's the difference between "pervasive" and "ubiquitous"?
Pervasive describes things that spread through a place to become established everywhere.
Ubiquitous describes things that are everywhere in a place because it is the nature of that place to have those ubiquitous things.
The two words have slightly different origins -- Pervasive comes from pervade (to diffuse throughout) while Ubiquitous comes fro ubiquity (be everywhere).