It's like comparing jamón ibérico in Spain with ham in US. Completely different products.
We call "сало" "salo" in English. Cf. Wikipedia. Lard (смалець) is almost exclusively used for cooking (like oil) or as a spread for bread. Salo is its own thing.
I googled "сало" and looked (stared) at the pictures… Must be an acquired taste.
In Romania, they call it "slanina" and a lot of people like it. I. however, am not one of those people :-)
There was a musical group out in the 1970s called The Fatback Band. In the American south the term may be a little more well-known because it's used in preparing certain dishes more often than elsewhere.
I've never heard the word "fatback" in British English. What does it look like?. How is it used.? It sounds like very fat bacon.