Why am I getting two different outcomes on my W-2s?

Hi, I'm looking for advice on what might going wrong here. I started going through the free Turbo Tax edition, as I usually do because I rent and my taxes are simple, and I found that my W-2 will provide close to $2,000 in federal return and my wife's will take away so much that we'll owe a little over $100. I went to HR Block and filled in the exact same information and my wife's W-2 would have a $450 return and that mine would now cause us to owe around $50. I can't imagine how putting in the same information on two sites could have such drastic differences in what we owe. I also can't imagine how we owe anything. We've never owed taxes in the 13 years we've been together, I assume because of how much we chose to have taken out in taxes each paycheck. I'm not tax expert, but this is strange to me.