Lions/SanFran Touchdown?

[UES]

Can anyone help me understand why play below was over turned when a similar play that happened last year in the Lions/Bears game was ruled differently? Below is a summary of the play from yesterday's game:

In the fourth, Stafford connected with Nate Burleson on a 5-yard pass into the end zone that was ruled incomplete on the field. It was overturned after video review, giving Detroit a 19-15 lead. Burleson caught the ball and got both feet down, then lost the ball after tumbling beyond the end zone -- a play similar to Calvin's Johnson's well-documented play in the end zone that was ruled incomplete last year at Chicago.

I am not a football official just wondering what the ruling is? Thanks