When Britain voted to leave the European Union in June, Donald Trump quickly cheered the results and later dubbed himself "Mr. Brexit."

Trump believes he'll win the U.S. election and shock everyone, just like the Brexit vote stunned the world.

After all, the real Mr. Brexit, Nigel Farage, is backing Trump, and Brexit supporters wanted stricter immigration laws, new trade deals and to "take back the country" -- ring a bell?

But comparing the surprise Brexit vote to the U.S. election is misguided, according to two reports published Wednesday by Goldman Sachs and investment firm Cowen and Co.

Together they lay out several key arguments:

Related: Brexit is becoming a big fat mess

1. Polling in the U.K. before Brexit was much closer, and inconsistent, than it has been for the U.S. election. Hillary Clinton has a healthy lead in CNN's Poll of Polls, which averages results from recent polls.

2. Brits were voting for an idea. Americans are voting for a person. That's key. Consider this: Only 29% of Americans believe the country is heading in the right direction (idea), yet President Obama (person) has a 52% approval rating.

3. Demographics between the United States and Britain are very different. Clinton has a big lead among Latinos, the largest-growing segment of the U.S. population. Cowen argues there's no comparable demographic in the U.K.

4. Brexit was a popular vote. The U.S. election has the electoral college. If a candidate wins the majority of votes in a state, he or she wins all the electoral votes in the state.

5. Millions of Americans vote before Election Day in early voting. That wasn't an option for Brexit. So far, early voting suggest stronger participation among Democrats.

Related: A Trump win would sink stocks. But what about Clinton

"The early vote continues to break for Clinton as we struggle to construe a realistic path for Trump to hit 270 [electoral votes]," the number needed to win, Chris Krueger, senior policy analyst at Cowen, wrote in a report titled "6 reasons why Trump is not an American Brexit."

The experts know what you're thinking: you guys got the Republican primary wrong.

And political economist Alec Phillips of Goldman Sachs (GS)admits that -- he and his team assumed voters would rally around another Republican candidate. They didn't put much weight on the primary polls at the time, which did favor Trump.

So they learned their lesson and are now putting more weight on the polls, most of which show Clinton with a solid lead. In the latest CNN/ORC poll, Clinton leads Trump 49% to 44%, respectively.

Of course, Trump could still win and become America's Mr. Brexit. And that's where similarities may outweigh differences: economists say Trump's trade policies and pro-Brexit proposals would significantly hurt either country.