I can't even fathom losing either so I am just not going there.
However, I will say that I love my DD so, so much. Beyonds words, I cannot describe a mother's love for her child. And yet, the love I have for my husband is also beyond my belief. It is different, those 2 loves. My "job" is to prepare my daughter for life. Someday she'll go to college and then she'll go out into the world making a life for herself.
It is because of that that I want and need to keep my relationship with my DH a good one. I don't want to be 'strangers" when she's gone. I wan to be prepared for several more years of the two of facing what comes our way both good and bad. I'm hoping for more good than bad.
So, my answer is that it is just a different kind of love. That is the wonderful thing about love---there are different kinds and enough of it to go around for everyone.