Saliva tests & PCR tests are both accurate ways to check for traces of covid-19. The way to tell them apart is by looking at how the tests are conducted. With saliva covid-19 tests, you’re asked to share a sample of your saliva. This is then sent off to a lab, where the saliva sample is tested for covid-19. As for PCR tests, a swab is used to collect a sample from your nose & throat. This is then tested in a lab for traces of covid-19.