Former Florida Gov. Jeb Bush listens before speaking to a group at a Politics and Eggs event at The New Hampshire Institute of Politics in Manchester, NH on Friday April 17, 2015. (Jabin Botsford/The Washington Post)

It’s often said by detractors of the presidential nomination process that it ought not to begin in two small, predominantly white states like Iowa and New Hampshire. But as Republicans will be reminded this weekend, Iowa and New Hampshire can be strikingly different in the political challenges and tests they offer candidates.

Iowa has already had two cattle calls for candidates this year. This weekend, New Hampshire takes center stage. The slew of candidates and a schedule of events —highlighted by the state GOP’s forum Friday and Saturday — will make it feel almost like the final days before next winter’s first-in-the-nation primary.

It will be a weekend of high political rhetoric, intimate house parties, diner visits and quiet courtship of key activists. Anyone on the roads of southern New Hampshire the next few days is likely to drive past somebody who wants to be president in 2016.

Iowa and New Hampshire share a fierce pride in being at the front of the nomination process, but there is little they share in common in terms of political terrain or in the bragging rights. A look at the results over the past three decades is a reminder that what works in Iowa doesn’t necessarily work in New Hampshire.

Dating back to 1980, no Republican candidate other than a sitting president has won both the Iowa caucuses and the New Hampshire primary. George H.W. Bush won Iowa in 1980, but Ronald Reagan came back to win New Hampshire and eventually the nomination. Eight years later, Robert Dole won Iowa in 1988, but Bush came back to win New Hampshire and the nomination.

But the pattern of New Hampshire winners capturing the nomination was broken in 1996. Dole, the eventual nominee, won Iowa but was upset in New Hampshire by Patrick Buchanan. In 2000, George W. Bush cruised in Iowa and was crushed by John McCain in New Hampshire.

Eight years later, the earlier pattern reasserted itself. Mike Huckabee won Iowa, but McCain saved his candidacy by winning New Hampshire. In 2012, Rick Santorum edged Mitt Romney in Iowa, and Romney trounced the field in New Hampshire and later became the GOP nominee.

What makes the two states different is the nature of their caucus and primary electorates. Exit polls from 2012 tell the story. In Iowa, religious and social conservatives have come to dominate. In New Hampshire, New England’s mix of fiscal conservatism and social moderation is the reality.

In Iowa, 58 percent of the 2012 caucus attendees described themselves as evangelical Christians, compared with just 22 percent in New Hampshire. In Iowa, 47 percent said they were “very conservative,” compared with just 21 percent in New Hampshire. But 47 percent of those who turned out in New Hampshire said they were moderate or liberal, while just 17 percent of the caucus electorate in Iowa described themselves that way.

In 2012, 25 percent of Iowa caucus attendees said they wanted a true conservative as their nominee, compared with 13 percent in New Hampshire. Granite State GOP voters prized experience far more than Iowans did. Iowans were more likely than New Hampshire voters to support the tea party.

New Hampshire’s GOP primary electorate included a higher percentage of college graduates than Iowa’s and more voters with incomes over $100,000. In both states, however, men significantly outnumbered women in the caucuses and primary.

What has made the two states so different is the role of independents, who can exercise considerable power in New Hampshire compared with Iowa. Four years ago, almost half of the New Hampshire primary voters described themselves as independents. In Iowa, independents comprised just 23 percent of the caucus electorate.

Iowa has faced many questions of late about the value of its caucuses. Are they a true test for all candidates or a contest mostly among the most conservative candidates in the field? Can someone who wins Iowa appeal broadly enough to win the nomination? The fact that neither Huckabee nor Santorum became the party’s nominee has caused plenty of concern among mainstream Iowa conservatives.

New Hampshire voters have resisted rubber stamping the results in Iowa and seem to have a penchant for keeping front-runners humble.

That was certainly the case in 2000, when McCain beat Bush, and as much the case in 1996 with Buchanan’s victory over Dole. Those two upsets rewarded Republicans of sharply different ideologies. What Buchanan and McCain shared was the DNA of an insurgent. Both were outsiders battling against bigger forces and appealing to voters not to let the nomination process end after only two events.

Social conservatives are likely to dominate Iowa again, but who eventually emerges in the top ranks is an open question today. New Hampshire likely will be hospitable to some other candidates. But it, too, looks wide open. How this will all shake out in 2016 awaits another day. Iowa has taken an early turn. This weekend begins the real conversation in the Granite State.