Ay iba talaga ang tatlo, mama! Antigen test (yung rapid test na mabilis ang result, usually 15-30 mins lang) versus swab test, ang swab ay mas accurate kasi laboratory-based, pwedeng PCR or antigen, pero kailangan maghintay ng result usually next day pa. One of my mum friends swears na kapag exposed kami, sini-schedule namin agad ang PCR swab kasi mas reliable especially kung may symptoms na, pero kung quick check lang before mag-attend ng event, antigen rapid test na lang ang ginagamit namin dahil convenient at instant agad makikita mo if positive or negative. Both require nasal/throat swab pero different ang processing, yan ang main difference really!