A small gaggle of anti-Donald Trump protesters stood along a police barricade on lush San Vicente Boulevard in my adopted home town of Santa Monica on Wednesday evening. Many of them backed Sen. Bernie Sanders (I-VT), and between shouts of “Dump Trump” (and worse), they debated whether Sanders and Trump are in fact the same.

The idea horrified one middle-aged woman, but a few of the men said they were confident some Sanders fans would vote for Trump over Hillary Clinton.

Certainly, Sanders and Trump are tapping some of the same reservoirs of public discontent. Voters on both sides feel that their respective parties are beholden to special interests in Washington, D.C. The slow pace of the economic recovery has left many Americans with a deep sense of uncertainty — so deep that for the first time in 130 years, young Americans are most likely to live with their parents than on their own. And as William Galston recently pointed out in the Wall Street Journal, two decades of Chinese competition have left Americans more skeptical about free trade deals, which Sanders and Trump both oppose.

But another observation in the Wall Street Journal — this time by Karl Rove — shows how different the Sanders and Trump insurgencies really are. Rove notes that Sanders has managed to appoint radicals — “Sandernistas” — to the Democratic Party platform committee. Their intent is to shift the party even further to the left on every issue, from climate change to Israel.

In contrast, Trump is not actually shifting the Republican Party’s positions on any major issues — not even on trade. The 2012 GOP platform welcomed free trade agreements, but stipulated that “a Republican President will insist on full parity in trade with China and stand ready to impose countervailing duties if China fails to amend its currency policies.” That is essentially the same as Trump’s policy. (For daring to campaign on what the party theoretically already believes, he is called dangerous.)

Trump is certainly taking a different position on immigration than the one the GOP elite staked out in its “autopsy” of 2013, when insiders attempted to impose a liberal immigration policy by fiat. But his border stance is little different to Sen. John McCain’s (unfulfilled) promise in 2010 to “complete the danged fence.”

The essence of Trump’s insurgency is tactical: he challenges the media and the cult of political correctness, before which other Republicans have cowered — and he wins.

Sanders, on the other hand, is attempting a real change in what the Democratic Party actually believes. Or, alternatively: Sanders wants to finish what Barack Obama started in 2008, when it still had to be shrouded in euphemisms, pandering, sockpuppetry and lies.

Sanders promises: punitive taxes on the rich; government health care for all; free college; amnesty for illegal aliens, radical cuts to the military; and Israeli surrender. Obama took big steps towards these goals, but Sanders wants to cement them.

Until now, the Democratic Party elite has been able to resist the leftist tide within its ranks. In 2012, when the party platform committee removed traditional planks on God and the status of Jerusalem, the leadership staged a clearly fraudulent floor vote at the Democratic National Convention in Charlotte to amend the document and save face.

Today, the left, inspired by Obama’s unrestrained second term, and energized by Sanders’s unlikely success, is determined to make those policy changes — and make them stick.

Some conservatives worry about Trump because his insurgency is not ideological. Nor is it a cult of personality: it is simply a rejection of the GOP leadership, which has failed to stop Obama through confrontation or compromise. But the radical left, with few exceptions, is not worried about Sanders’s rise, because he is one of their own.

Trump wants to restore America’s “greatness”; Sanders wants a “political revolution.” These are different — and incompatible — goals, and movements.

Joel B. Pollak is Senior Editor-at-Large at Breitbart News. His new e-book, Leadership Secrets of the Kings and Prophets: What the Bible’s Struggles Teach Us About Today, is on sale through Amazon Kindle Direct. Follow him on Twitter at @joelpollak.