Not the same thing at all...

The boy Clegg seems to be (as ever) under the misunderstanding that matters of conscience are interchangeable with similar legislation. He believes that MP's should not be allowed a free vote on 'Gay marriage' because they weren't given one on 'Civil Partnerships'.
Telegraph.

The Deputy Prime Minister said Liberal Democrat MPs will be forced to vote in favour of allowing gay marriage when the legislation is considered by Parliament.
Some Tory MPs are strongly opposed to allowing gay marriage. Last week Sir George Young, the Conservative leader of the Commons, announced that there would be a free vote on the subject because it was a matter of conscience.
But Mr Clegg disagreed, pointing to the fact that the original law bringing in civil partnerships was also not passed on a free vote in the House of Commons.
He the BBC’s Andrew Marr porgramme: “My view is that in the same way that the civil partnerships legislation that was introduced under Labour was a whipped vote, I personally don’t think this is something that should be subject to a great free-for-all because we’re not asking people to make a decision of conscience about religion.”
Mr Clegg said gay marriage was not “a matter of conscience” because the Government was not forcing churches to marry homosexual couples.

What Clegg is missing of course is the exact connotation of the word marriage. It doesn't matter if the government forces churches to marry gay people or not (something that they know they'd lose) but because the term marriage is a religious one and therefore is a matter of conscience. Marriage is a religious ceremony to join together a male and female for the purpose of bringing children into the world. Calling a civil partnership a marriage is wrong simply because the two terms are not interchangeable. What the government are doing is attempting to change the basis of a religious state into a civil one. This in essence is why the 'Gay Marriage' debate is a matter of conscience to many MP's not because they are opposed to gays living together or having the same rights as married couples, but because the term 'marriage' has a far different meaning to them than it does to the likes of Cleggy boy and various other parliamentarians on the liberal left including Cameron himself.
That is why it's a matter of conscience and that is why as usual Clegg is wrong to insist his MP's vote the party line.