Blood work help

Ma

I’m 13 weeks +1 yesterday went for 2d is genetics after us I was then sent to get blood work they pricked finger put on card Then was told results take 7 + day I go to leave lab tech camped out say sorry It was supposed to be blood draw not finger but this test will come back in a day or two and determine the gender ?? I thought they got that from finger stick ?! Does anyone know the difference between the 2 test