What is the difference between blood type and dna?

I am trying to figure out of 2 men i had sex with which is the father of my child. My child is B+ I am O- and one of the men he is A+, is it possible that he is the father. I called the dna lab and they said that blood type and dna are 2 different things that they use that in the old days when dna test were not around so my thing is if it was good back then why not today. Can some one help me in the difference between blood type and dna.What is the difference between blood type and dna?
DNA is the specific genetic code that makes you who you are. Your DNA is specific to you, and no one else.



Blood type refers to the antigens that are present in your blood- there are four basic blood types- A, B, O and AB. Everyone has one of these four blood types.



You can disprove paternity with blood type, but you cannot prove it. In other words, you can say it is not possible for someone to be the father, but not that one specific person is definitely the father. That is why DNA is now used- it removes all guesswork.