I have a question about fillings. Is the color A2 Yellow? If so, is the teeth color A1 considered White?

both are on yellow side. shade matching is dentist's issue , not yours. just tell yr dentist to do proper shade matching.

None of us have truly "white " teeth...all have some yellow in them and even blue or gray and brown and pink.These are in the same shade spectrum(yellowish or warm undertones), A1 is just a little lghter than A2. I get compliments on my white teeth(which I haven't bleached) and they are more in the gray scale,D2. It's like skin tone...we are all unique and thank heavens ,we are!

Shades A1 and A2 are both in the yellow range of colors with A2 being a deeper amount of color than A1.  Neither of them are "white" because teeth are not naturally white.  To get into white you have to start talking about bleach shades.  Hope that helps.