The difference is the Substratum exit nodes are indistinguishable by the website, Tor exit nodes are recognized by most websites and blocked by some.
The Sub nodes encrypt the data sent so the exit nodes cannot see your information.  Tor exit nodes have all your information available. NSA and hackers use directed tor exit nodes to spy and steal information.
There are products that use the same routing methods substratum uses now but they rely on the trust of a human " a third party auditor " to
ensure your privacy and information is not stored.
Substratum uses the blockchain to ensure privacy and security of your information.
In Blockchain We Trust
https://arstechnica.com/information-technology/2018/04/how-to-keep-your-isps-nose-out-of-your-browser-history-with-encrypted-dns/

This project will succeed but there are alot of people, corporations and governments that dont want it to. Since this will stymie a country or corporations abilities to censor and collect information on its users or citizens. Also hinders the Cloud Act and Net Neutrality control in the united states.

Also for anyone thinking Substratum is a scam, Remember this coin was sold in the United States.
Digital currencies sold in the United States are considered securities under the Securities Act
https://www.sec.gov/litigation/investreport/34-81207.pdf