• Elon Musk and Bill Gates have been feuding over everything from the coronavirus to electric vehicles.
  • The two moguls don't see eye to eye on electric-car technology. Musk has said Gates doesn't know what he's talking about, and Gates has said he bought a Porsche electric car over a Tesla.
  • This year, Gates and Musk have feuded over the coronavirus. Gates called Musk's comments on the outbreak "outrageous," and Musk recently described Gates as a "knucklehead."
  • Now, there's a new development in their rivalry: Musk has surpassed Gates as the world's second-richest person. 
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Bill Gates and Elon Musk don't exactly see eye to eye.

While the Microsoft billionaire and the Tesla and SpaceX titan have never had a particularly cozy relationship, things have heated up over the past six months as the two have openly sparred about everything from electric vehicles to the coronavirus.

The two moguls are among the world's wealthiest, eclipsed only by Amazon CEO Jeff Bezos. While their public spats may not always be serious, they do appear to fundamentally disagree about the coronavirus — and as major players in virus treatment and an eventual vaccine to protect against it, their clashes carry even more weight.

Here's where the friction between Gates and Musk began and everything that's happened since.

Gates doesn't appear to be a fan of Tesla vehicles, and he's said as much publicly.

Bill Gates. (Getty)

In February, Gates said during an interview with the YouTuber Marques Brownlee that while Tesla had helped to drive innovation and adoption of electric vehicles, he recently bought a Porsche Taycan.

Gates' comments didn't get by Musk, who tweeted that his conversations with Gates had always been "underwhelming."

But things really heated up in July when Gates took issue with Musk's comments on the coronavirus pandemic.

In an interview on CNBC's "Squawk Box," Gates criticized Musk's comments on the virus and implied that Musk shouldn't be speaking about the pandemic at all.

"Elon's positioning is to maintain a high level of outrageous comments," Gates said. "He's not much involved in vaccines. He makes a great electric car. And his rockets work well. So he's allowed to say these things. I hope that he doesn't confuse areas he's not involved in too much."

Gates and Musk are involved in fighting the coronavirus, with Gates pledging $100 million to fight the virus via the Bill and Melinda Gates Foundation and Musk redirecting Tesla resources to source and produce ventilators and teaming up with the German biotech firm CureVac — in which Gates is an investor — to make a device to aid in vaccine production.

But since March, Musk has frequently downplayed the severity of the virus and strongly criticized stay-at-home orders. He's promoted the malaria drug hydroxychloroquine as a treatment for the virus, falsely said that children are immune to it, and questioned coronavirus-deaths data.

Musk also said March that there would be "close to zero new cases" by the end of April. The death toll in the US alone recently surpassed 200,000.

The comments struck a nerve with Musk, who taunted Gates on Twitter.

Elon Musk, founder and chief engineer of SpaceX speaks at the 2020 Satellite Conference and Exhibition March 9, 2020 in Washington, DC.

Musk jokingly posted multiple tweets about Gates, including "Billy G is not my lover" and "The rumor that Bill Gates & I are lovers is completely untrue."

Earlier this month, Musk tweeted that Gates had "no clue" about electric trucks.

Bill Gates, takes part in a panel discussion titled "Investing in African Prosperity" at the Milken Institute Global Conference in Beverly Hills, California May 1, 2013.

In August, Gates wrote a blog post about electric vehicles that questioned whether it was practical to make vehicles like 18-wheelers fully electric.

Though he didn't mention Tesla, the company does produce a semi.

A few weeks later, a Twitter user asked Musk about his opinion of Gates' comments, to which Musk replied, "He has no clue."

Musk recently called Gates a "knucklehead" for criticizing his coronavirus efforts.

During a podcast interview published this week, The New York Times' Kara Swisher asked Musk about his feelings about the virus, including whether he planned to get vaccinated.

Musk defended himself against Gates' comments, saying he'd spent time with Harvard University epidemiologists "doing antibody studies" and noting Tesla's work with CureVac.

"Gates said something about me not knowing what I was doing," Musk told Swisher. "It's like, 'Hey, knucklehead, we actually make the vaccine machines for CureVac, that company you're invested in.'"

Now, there's a new layer to their rivalry: Musk surpassed Gates as the world's second-richest person. His net worth now stands at $128 billion.

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