Both tests determine COVID-19 current infection status, however they have very different use cases.
PCR testing is considered the “gold standard” in SARS-CoV-2 detection. This test actually detects RNA (or genetic material) that is specific to the virus and can detect the virus within days of infection, even those who have no symptoms.
Antigen testing detects protein fragments specific to the Coronavirus. It can be done in a clinic, doctor’s office, or hospital. Turnaround time for results can be reported within 15 minutes. This is NOT a diagnostic test and should only be used for certain purposes like screening.