Rolls-Royce (LSE: RR) and Nvidia (NASDAQ: NVDA) shares have treated investors to extraordinary returns. I own both and have done well, although I didn’t get in early enough to enjoy the fabulous gains some have made. Now I’m wondering which stock market hero has more to offer from here.

They’re two of the great growth stories of recent years. Nvidia has ridden the AI revolution, while Rolls-Royce has transformed itself into a leaner, more profitable engineering business.

UK and US stock market stars

The numbers are astonishing. Nvidia shares are up 882% over five years, while Rolls-Royce has somehow done even better, rocketing 1,214%. Both have slowed recently. Nvidia is up about 31% over the past year and Rolls-Royce 36%.

Nvidia’s latest results show why investors remain excited. Second-quarter revenue hit $96.2bn, up 106% year on year, while data centre revenue surged 117% to $89bn. Its latest products and huge spending on AI infrastructure could keep demand strong for years. But with a $5.4trn market cap, the numbers need to be big.

Rolls-Royce continues to grow rapidly too. 2025 revenue rose 12% to £20.1bn, while underlying operating profit jumped 41% to £3.5bn. Free cash flow climbed 35% to £3.3bn. Management has again raised its targets, but investors can’t expect it to smash expectations forever. Much of the easy turnaround work has already been done.

Comparing the valuations

So which offers better value? Nvidia has the edge here, I feel. Its price-to-earnings ratio is 28.4, compared with a hefty 40.6 for Rolls-Royce. It has been as high as 50, but recent weeks have been bumpy.

Nvidia’s dividend yield is only 0.45%, while Rolls-Royce offers 0.75%, so neither is remotely a classic income stock. But both should be able to lift payouts as profits and cash flow grow.

Nvidia’s biggest risk is that the AI boom fails to justify the enormous sums being spent on it. There are also concerns about circular financing, with it investing in companies that are also buying into the AI ecosystem and its products. A slowdown in AI capital spending could hit Nvidia hard.

Rolls-Royce has different risks. Its share price already takes into account a lot of success and the aerospace industry is cyclical. A weaker economy or aircraft engine technical or delivery issues could knock the stock off course.

The long-term investment view

Both companies still have huge opportunities. Nvidia is building the computing infrastructure behind a technological revolution. Rolls-Royce has strong positions in civil aerospace, defence and power systems and is generating serious cash. Small nuclear reactors offer a huge potential growth area, but that’s over decades. There will be bumps along the way.

Nvidia is worth $5.4trn. Rolls-Royce is a relative minnow at about £122bn. That arguably gives Rolls-Royce more room to grow.

Both are still worth considering with a long-term view, but neither can reasonably be expected to repeat their spectacular gains. As interest rates rise and markets wobble, I’d approach both with caution today. I might consider buying them on a dip. Otherwise I can see other smaller, nimbler FTSE growth prospects out there.

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Harvey Jones owns shares in Nvidia and Rolls-Royce.