(CNN) Classroom lecture vs. rock concert.

That's one way to quickly characterize the difference between a campaign stop for Hillary Clinton and Bernie Sanders.

When Democrats visit political events for these two presidential candidates, it's a markedly different experience.

For months, crowds have been a central part of the Sanders strategy, a critical ingredient in how he has overtaken Clinton in early New Hampshire polls, come within striking distance in Iowa, and has raised nearly as much money. The idea behind the big rallies -- in college towns and elsewhere across the country -- was hatched by his small team of advisers to elevate Sanders, surrounding him with tens of thousands of people.

For Clinton, the calculation has been different. Democrats have already seen her on the big stage, so the decision was made to intentionally make her events small, so she could build a more direction connection with voters.

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