Gay Marriage vs Gay Civil Unions

This is an excerpt from an MSNBC article that I read today by Debra Rosenburg. It made a lot of sense...
So not calling it marriage makes a big difference?
One of the main protections that comes with marriage is the word "marriage" and the security and certainty that come with that. There's not a married couple in the country that would trade in their marriage for a civil union or something else. Marriage is more than just the legal protections and responsibilities. It's a statement, a commitment that everyone recognizes. The best way to think about it is ask yourself this question. Either marriage and civil unions are the same—in which case why do we need two lines at the government clerk's office—or they're not the same, in which case why is the government withholding from these families and what reason does it have for doing that. It's funny because when we're discussing this question on the one hand, pretty much everyone agrees that marriage matters. And people have emotions and a rich set of feelings about marriage. But when the question is can gay people be denied marriage, people say it doesn't matter at all. How can it matter and not matter?