Both candidates are blanketing the state in the closing days of the first-in-the-nation caucus -- that's obvious. But that's where the similarities end.

The secret to the Iowa caucuses is this: Not all caucus sites are created equal. Each of Iowa's 99 counties has a set number of delegates available based on turnout in the most recent statewide election, meaning less populous counties have far fewer delegates.

In rural counties, a win could mean gaining one or two delegates. In urban counties, however, campaigns have a better chance of running up the score and possibly winning dozens of delegates in the process.

The winner on caucus night is the person who has won the most delegates, not the person with the most caucus-goers. In fact, the Iowa Democratic Party does not release turnout numbers by caucus site.

Aides and strategists from both campaigns know all that, of course, but they are taking very different tacks.

Clinton, who ran a third-place campaign in Iowa in 2008, is focusing more on delegate-rich cities and urban areas. The hope is that by running up the score in Davenport, Cedar Rapids and Des Moines -- more urban areas in a primarily rural state -- Clinton will be able to pad her delegate total.

By Monday, Clinton will have held 40 open press events in Iowa in 2016. The counties she will have visited have an average of 68 delegates up for grabs.

"As we come in to the final days, we are focused on turning our people out ... focused on increasing and maximizing support and ... making sure we are in the right places," said Matt Paul, Clinton's Iowa campaign manager.

Sanders, on the other hand, has spent much of January focused on smaller counties with fewer delegates. He has visited Jackson County (9 delegates), Hardin County (7 delegates) and Buchanan County (10 delegates) and has spent considerable time turning out big crowds of supporters at colleges in these small delegate counties.

Sanders will have held 44 Iowa events in 2016 by Monday. But his average delegate total -- at 58 -- is 10 less than Clinton.

This is by design, says Pete D'Alessandro, the head of Sanders' Iowa campaign.

"This is different than an election. This isn't one person, one vote," D'Alessandro said. "The difference in a caucus situation is you can actually saturate to the point, even if you have a huge lead or you are very popular, in one area."

Sanders' Iowa campaign is well aware of this. Earlier this week, the Vermont senator held a rally with over 2,000 people at Luther College in Decorah. The size of the crowd was impressive to Sanders' aides. But those watching knew that Winneshiek County, where the event was held, has only 11 delegates up for grabs.

"It is the same number of delegates going to the state convention if you got 200 or 2,000 people," said Rep. Dave Loebsack, a Clinton supporter, about Sanders' event at Luther College. "I think it's good for Hillary because I think her support is clearly spread out throughout the state and they have been working on it for a longer amount of time."

So why would Sanders go to Luther? His approach is "surgical," said D'Alessandro. "Even though it is smaller, hey, if we can get 14 more people to that caucus, we actually win another delegate."

But there is a problem with this plan. There is a ceiling on how many delegates Sanders can win in these small counties, even if his campaign turns out thousands of people.

To counteract that problem, Sanders' campaign is urging college students - who are able to caucus in their hometowns or where their college is located - to go home to caucus. This will spread out the Sanders support, his aides hope, and allow him to use his support among young people to help him in more urban counties.

D'Alessandro said the campaign has also had to deal with the fact that Clinton has run in Iowa before, even if she lost badly in 2008.

"One of the myths of the Iowa caucuses is that Hillary Clinton didn't run a good campaign in 2008," he said, noting she still started the 2016 race with a list of hundreds of people who backed her previously able to step in this time around.

Sanders' strategy reflects these comments. In the last month, Sanders is only making four stops in counties Clinton won in 2008, including none in the final weekend before the caucuses.

On the other hand, Clinton has focused most of her time in counties she lost in 2008. From January 1 to February 1, Clinton will have made only six stops in counties she won eight years ago.

The strategy positions Clinton to over-perform in areas that Barack Obama and John Edwards won in 2008, her aides hope, leading to decisive wins in Iowa's handful of cities. Clinton's campaign has also deployed a fleet of surrogates to rally supporters in areas she will not visit.

"It is critically important in the caucuses that you respect that these caucuses are about relationships and you build those relationships with your organizers and your volunteers overtime," Paul said. "We have built, since April, (an operation) to do this on a statewide level so that we are engaged with, talking to and listening to Iowans no matter where they are in a number of different ways."