What is the difference between slavs and Russians?

Answer 1

All ethnic Russians are Slavs, yet not all Slavs are Russians.

Russians, along with Ukrainians and Belarussians, are all Eastern Slavs.

Eastern Slavs, along with the Western Slavs(Poles, Czechs, Slovaks) and the Southern Slavs (Serbians, Slovenes, Bosnians, Croats, Montenegrins, Bulgarians, Macedonian Slavs) are all Slavs.

NOTE: I only mentioned the SLacic groups that have their own nations, there are other Slavic peoples that from minorities in various places in Eastern Europe.

Answer 2

Slavs are an ethnic group that encompasses various Eastern European nationalities, including Russians. Russians specifically refer to people from the country of Russia. So, all Russians are Slavs, but not all Slavs are Russian.