It was a night of both friendly collegiality and substantive debate. Tonight's Democratic debate in Los Angeles drew out real differences and demonstrated clear commonalities between Sens. Barack Obama and Hillary Clinton. It's worth reading the transcript of the debate - scrolling through it, you'll get a very clear sense of what the candidates stand for, oppose, and where they differ.

A few notable moments illustrated the differences between the candidates. I've rounded up a few of those below.

Sen. Barack Obama explained why his health care plan doesn't include a mandate for all Americans to obtain health care coverage, and disputing the number of American who would be uninsured under his plan:

...I think that it is important for us to recognize that if, in fact, you're going to mandate the purchase of insurance and it's not affordable, then there's going to have to be some enforcement mechanism that the government uses. And they may charge people who already don't have health care fines or have to take it out of their paychecks. And that I don't think is helping those without health insurance. That is a genuine difference.

Every expert who looks at it says anybody who wants health care will be able to get health care under my plan. There won't be anybody out there who wants health care who will not be able to get it. That's point number one. So the estimate is -- this is where the 15 million figure comes in -- is that there are 15 million people who don't want health care. That's the argument.

Senator Hillary Clinton countered, claiming that health insurance under her plan would be affordable and that universal health care is a shared moral responsibility:

So when you draw the distinction that, well, it's not affordable, therefore people will have to be made to get it, well, the fact is it has been designed to be affordable with health care tax credits.

And it's also important to recognize that right now there are people who could afford health care. And they're not all young; they're people who just don't feel they have to accept that responsibility. There are many states which give families the option of keeping children up till 25 on their policies, but their rates of uninsurance are still very high. We cannot get to universal health care -- which I believe is both a core democratic value and an imperative for our country -- if we don't do one of three things: either you can have a single payer system, or -- which I know a lot of people favor, but for many reasons is difficult to achieve -- or you can mandate employers -- well, that's also very controversial -- or you can do what I am proposing, which is to have shared responsibility.

Obama responds to shared moral responsbility: If people are gaming the system, there are ways that we can address that, by for example making them pay some of the back premiums for not having gotten it in the first place.

Setting himself in opposition to Sen. John McCain, Obama affirmed his willingness to raise taxes on wealthy individuals:

If John McCain, for example, is the nominee, I respect that John McCain in the first two rounds of Bush tax cuts said it is irresponsible; that we have never before cut taxes at the same time as we are going into war. And somewhere along the line the Straight Talk Express lost some wheels -- (laughter) -- and now he is in favor of extending Bush tax cuts that went to some of the wealthiest Americans, who don't need them and were not even asking for them.

Moderator Wolf Blitzer looked for confirmation on that from both candidates:

When you let -- if you become president, either one of you let the Bush tax cuts lapse, there will be, effectively, tax increases on millions of Americans.

SEN. OBAMA: On -- on -- on -- on wealthy Americans.

SEN. CLINTON: Yeah, that's right...

SEN. OBAMA: I'm not bashful about it.

SEN. CLINTON: Absolutely, absolutely.

On immigration, both candidates asserted their support for a path to legalization, though Clinton does not support driver's licenses for undocumented immigrants.

Clinton on immigration: I believe that in many parts of our country, because of employers who exploit undocumented workers and drive down wages, there are job losses. And I think we should be honest about that.

Obama on immigration: And if we have signed them up -- if they have -- if we have registered them, if they have paid a fine, if they are learning English, if they are going to the back of the line, if we fix our legal immigration system, then I believe we will not have this problem of undocumented workers in this country because people will be able to actually go on pathway to citizenship.

While Clinton did not commit to withdrawing all combat troops within 16 months of his inauguration, as Obama has, she said she would begin withdrawing troops within 60 days of taking office and would begin drawing up an exit strategy on the first day of her presidency. Obama explained why an end date is important:

And the reason I think it is important is because if we are going to send a signal to the Iraqis that we are serious, and prompt the Shi'a, the Sunni and the Kurds to actually come together and negotiate, they have to have clarity about how serious we are. It can't be muddy. It can't be fuzzy. They've got to know that we are serious about this process...

But the one thing that I think is very important is that we not get mission creep and we not start suggesting that we should have troops in Iraq to blunt Iranian influence.

Clinton on her war vote:

I warned, at the time, it was not authority for a pre-emptive war...So I think I made a reasoned judgment. Unfortunately the person who actually got to execute the policy did not. [There's much more in her reasoning in the transcript -- check it out and see if you buy it.]

Obama made it clear that recent improvements in Iraq do not mean we're winning:

But the notion that somehow we have succeeded as a consequence of the recent reductions in violence means that we have set the bar so low it's buried in the sand at this point.

Clinton dodged an opportunity to define clearly a campaign role for her husband that does not include attacking Obama and stirring up race-based tension. Instead, she took the question as an implied slight against her, and the American people's willingness to trust her with the job:

And I know that as we go forward in this campaign, it's a choice between the two of us. And we're proud of our spouses. We're proud of our families. We're proud of everybody supporting us. But at the end of the day, it's a lonely job in the White House. And it is the president of the United States who has to make the decisions, and that is what I'm asking to be entrusted to do.

But my living room exploded with cheers and claps when Wolf Blitzer told the candidates, "The more I speak to Democrats out there...all over the country, they take a look at the two of you and they see potentially a dream ticket, a dream ticket for the White House."

The crowd at the Kodak Theatre roared. Both candidates took the opportunity to talk about their vision of good governance, and Obama offered a diplomatic "I'm sure that Hillary would be on anybody's short list."