The COVID-19 swab test is used to detect if you currently HAVE the virus by taking a swab sample from your mouth (and sometimes your nose too), then it’s sent off to a specialist lab. These samples can also be taken at home but all samples must be sent to a government approved lab for analysis to ensure results are accurate and reliable.
An antibody test is a different type of test which looks for the presence of antibodies produced by the body when someone contracts COVID-19. This test can tell if a person HAS previously been infected at some point.
You can read more about tests here.