https://www.news-medical.net/health/How-does-SARS-CoV-2-Compare-to-SARS-CoV.aspx
They are both coronaviruses (86.85% similarity in genome) and they have similarities in transmission and survival time on surfaces, but the symptoms, severity, and incubation times are different. "SARS-CoV-2 is less likely to be fatal than SARS-CoV. However, SARS-CoV-2 is more easily spread." SARS had a case fatality rate of 9.6%, and COVID 19 is around 1.9% in the US.
Though 86% similar in genome, you should bear in mind that humans are 85% genetically similar to mice and 60% similar to bananas, chickens, and a cows.