Adguard seems to offer blocking only, whereas Privaxy "is able ... to inject scripts as well as styles into HTML documents", which was the feature my comment expressed interest in.
The readme goes on to say: "Privaxy is also way more capable than DNS-based blockers as it is able to operate directly on URLs and to inject resources into web pages."
In this case "incorrectly" is what makes it possible to find it, search-engine-autocorrect-stupidity aside. The name is obviously a combination of privacy and proxy. There's another one called Privoxy which works on similar principles.
