It’s been a little bit weird that Apple would sell both a 13-inch MacBook Air and a 13-inch MacBook Pro simultaneously, but perhaps never more than today — because Apple’s new $999 and $1,299 laptops seem nearly identical if you look beyond the differently curved frames. They’ve got the same M1 processor, the same memory and storage options, the same ports, and very similar screens.

I’m not joking when I say: the biggest difference is a fan.

This fan, which is exclusive to the MacBook Pro:

Render: Apple

I mean, yes, it is a little bit hilarious the MacBook Air is now a laptop that doesn’t blow air, just like it’s amusing that the Air technically continues to be a thicker laptop than the 13-inch Pro. (I guess it’s been a long time since manila envelopes were a thing.)

Image: Apple

Image: Apple

But you shouldn’t knock that fan, because here’s a little-known fact about today’s CPUs: they can almost all run far faster if you give them better cooling. A CPU’s thermal design power (TDP) in watts is a better predictor of performance than its gigahertz clock speed because some of the weakest laptop and phone chips can “boost” up to multiple gigahertz these days… until they heat up. In a small, fanless chassis, they have to throttle down quickly, but they can go for longer in a larger or better-cooled one.

That’s basically what’s happening in the new Apple M1-powered MacBook Air, MacBook Pro, and Mac mini, Apple confirms to The Verge. Each computer has the same exact processor (with one wrinkle I’ll address in a sec), which can theoretically run at the same speed — but the fan in the MacBook Pro and Mac mini lets them sustain peak performance for longer.

Render: Apple

Apple is trying to have it both ways, of course: during its presentation, it first lauded the MacBook Air for going fanless, then talked up the “active cooling solution” (aka the fan you’ve had for years) in the MacBook Pro. We’ll have to see which design is actually better in our upcoming reviews.

While the fan might be the most meaningful difference, it’s not the only one. Remember that wrinkle I told you about? Here it is, and more:

• At $999, the MacBook Air comes with seven GPU cores instead of eight, because Apple is salvaging some weaker chips (a common process known as binning) by disabling one core.
• But at $1,249, the MacBook Air has the same eight CPU cores and eight GPU cores as the $1,299 13-inch MacBook Pro.
• The 13-inch MacBook Pro has a slightly larger battery (58.2Wh vs. 49.9Wh) and quotes two additional hours of battery life compared to the MacBook Air.
• The 13-inch MacBook Pro’s screen is slightly brighter at maximum (500 nits vs 400 nits).
• The 13-inch MacBook Pro comes with the Touch Bar instead of physical function keys, though both have a Touch ID fingerprint sensor.

You might also be interested to learn that both laptops top out at 16GB of RAM, which is a current limitation of Apple’s M1 processor. Here’s Apple’s own spec comparison if you want to take a closer look.