Tesla vs. Rivian: Which Growth Stock Is a Better Buy?

Electric vehicle stocks have tested investors' patience recently. With high interest rates and cautious consumers, selling cars isn't as easy as it was a few years ago. This reality has hit both Tesla (TSLA +2.08%) and Rivian Automotive (RIVN +0.73%) hard. But despite these headwinds, investors are still assigning premium valuations to both growth stocks. With that said, these are two very differently sized companies, making a head-to-head comparison interesting. Rivian currently commands a market capitalization of about $20 billion, while Tesla's market cap hovers around a staggering $1.5 trillion as of this writing. With both stocks priced for significant future success, which one is the better buy today? Image source: The Motley Fool. Rivian: A weak fourth quarter and big guidance To Rivian's credit, the younger electric-vehicle (EV) maker just crossed a monumental hurdle. In 2025, the company delivered its first full year of positive gross profit. And in Q4 alone, Rivian generated $120 million in gross profit, translating to a 9% gross margin. But Q4 results took a hit as the company felt the whiplash from a huge third-quarter, when sales benefited from an enormous pull-forward in demand ahead of an expiring tax credit. Rivian's fourth-quarter total revenue came in at $1.29 billion, down from $1.73 billion in the year-ago period. More concerning, the company's automotive revenue plummeted 45% year over year in the fourth quarter. ExpandNASDAQ: RIVNRivian AutomotiveToday's Change(0.73%) $0.12Current Price$16.66Key Data PointsMarket Cap$21BDay's Range$16.14 - $16.8452wk Range$10.36 - $22.69Volume837KAvg Vol36MGross Margin-276.59% While Rivian's software and services segment was a bright spot, growing 109% year over year to $447 million, the core business of selling vehicles was under immense pressure during the quarter.With that said, this was primarily because the company had a surge in sales in Q3 ahead of the expiration of certain federal electric vehicle credits on Sept. 30. Capturing this dynamic, Rivian's third-quarter revenue soared 78% year over year. Probably a better indication of Rivian's underlying demand trends, when adjusted for the noise of recent quarter-to-quarter extremes, is the company's guidance. Management guided for total 2026 deliveries to be between 62,000 and 67,000. The midpoint of this guidance range translates to about 53% year-over-year growth. Tesla: A sprawling, diversified ecosystem Meanwhile, Tesla's automotive business is struggling. Yes, it could similarly blame a pull-forward in third-quarter demand for a weak fourth quarter, but Tesla also struggled on a full-year basis. The company delivered 418,227 vehicles in the fourth quarter of 2025 -- a 16% year-over-year decline. For the full year, total deliveries fell roughly 9% to 1.63 million. ExpandNASDAQ: TSLATeslaToday's Change(2.08%) $8.29Current Price$407.53Key Data PointsMarket Cap$1.5TDay's Range$402.11 - $416.3552wk Range$214.25 - $498.83Volume4MAvg Vol65MGross Margin18.03% But unlike Rivian, Tesla has a sprawling, highly profitable ecosystem to fall back on while it waits for the automotive market to recover. Consider the company's energy generation and storage segment. Tesla deployed a record 14.2 gigawatt-hours of energy storage in the fourth quarter -- an 29% year-over-year jump. And then there's the company's software momentum, which is much more significant than Rivian's. Tesla ended the year with 1.1 million active Full Self-Driving (Supervised) subscriptions, a 38% year-over-year increase. As Tesla's installed vehicle base grows, its popular Full Self-Driving (Supervised) subscription will likely become a lucrative revenue stream for the company. And this software is the foundation for its autonomous ride-sharing service, Robotaxi, which is still in its early innings -- and this could morph into a major business for Tesla, too. Finally, despite weakness in its automotive business, the company is still generating tons of cash. The company produced $6.2 billion in free cash flow in 2025, finishing the year with over $44 billion in cash and investments. Is Tesla or Rivian stock a better buy? Both stocks arguably feature stretched valuations today. At a roughly $1.5 trillion market capitalization and just $3.8 billion in net income, investors are already pricing in a massive acceleration in Tesla's software and fleet-based profits, as well as a recovery in its automotive sales. Still, if I have to put capital to work in one of these two EV makers, I'd rather pay a premium for a company with a long history of execution, a massive balance sheet, and a diversified business model. Rivian is executing well on profitability, but its net losses are still substantial ($3.6 billion in 2025), and the younger EV company is more dependent on automotive sales than Tesla, which is leaning into an energy business that is soaring and Robotaxi, which could become a meaningful profit driver over the long haul. Of course, Tesla is an extremely high-risk stock given its extraordinarily high valuation. But its more established, diversified business makes me think it will be the better performer over the long haul.