Lox means different things to different people.
The original Lox was heavily salt cured Salmon. It was used to transport salmon before the advent of refrigeration. It was not smoked. It's now almost impossible to find, but Gravlax is close, and without the salt overload of original Lox.
Now, for many, the word Lox has migrated to mean smoked salmon. Smoking being the critical thing.
Nova is a bit of a hybrid. It's Nova Scotia salmon (thus the name "Nova") which is lightly salt cured and lightly smoked. But it's name has also migrated, so now it can be made from any salmon not just Nova Scotia salmon. In fact, some great Nova is Atlantic salmon. The key point being lightly salt cured and lightly smoked.
In a nutshell you have 3 variables: 1) the species of salmon, 2) salt cured or not, 3) smoked or not.
Depending on the mix of these variables you get: Original Lox (some call it Belly Lox), Lox, Gravlax, Nova.
But if you want to push Lox to the limit just get the finest Scottish wild salmon from the river Tay and have it smoked in a smokehouse that's been in use for generations. It will taste amazing, but will cost you about $250/pound.
Content written and posted by Ken Abbott firstname.lastname@example.org