SARS-CoV-2 is a strain of the original SARS virus. To be a new strain genetic variation isn't enough. From what I have read I believe that you have to demonstrate a phenotypic (physical) change such as a antigen variation that alters the behaviour of a virus before it can be designated as a strain.
There are slight genetic variations in SARS-CoV-2 in different places with some researchers speculating that there may be 2 or even 3 main strains of SARS-CoV-2 but everything I've read so far suggests that these are not truly strains and that the genetic mutation rate of the virus is quite low which is encouraging for vaccine development.
Some papers do talk about strains of SARS-CoV-2 but reading the rest of the paper makes me wonder if a) I don't understand the term strain properly, b) the paper doesn't use the term strain correctly or c) strain isn't a firmly defined nomenclature?
https://www.sciencedirect.com/science/article/pii/S1567134820300915
The Daily Mail went with a headline claiming there were 30 strains which is just typically irresponsible Mail bullshit.