You would think an iPhone 7 is an iPhone 7, right? Apple’s famous for making one consistent device that’s the same inside, and works the same way, from carrier to carrier. So it’s a little surprising that one carrier’s version of the phone actually could work faster than another’s… and even more surprising that Apple’s set it up not to perform as well as it can.

The Verizon Wireless version of the iPhone 7 is technologically capable of downloading data at 600 Mbps over LTE. That’s super fast! But as two research firms told Bloomberg News, in practice the phone is not optimized, and can’t exceed 450 Mbps — the maximum download speed that the competing AT&T iPhone 7 can reach.

Now, granted, most users won’t notice the difference. Real-world tests, like the one PC Mag runs every year, find that the average 4G LTE connection speed you get ranges between 19 and 30 Mbps depending what city you’re in and which of the four major carriers you’re using. The top download speed recorded in their tests last year was 160 Mbps, on a Verizon phone in the northwest part of the country.

That means the 450 Mbps download speed a Verizon iPhone 7 limits itself to, and that AT&T users get, is still a solid four times faster than anything most users will ever be able to connect with.

iPhone parts are sourced from a whole bunch of different companies. It’s not just that one company makes glass and another makes CPUs and a third makes modems; for a huge number of internal components, there are several different manufacturers for each individual part, too.

That’s basically the key difference here, the research firms tell Bloomberg: the Verizon/Sprint model has a Qualcomm chip in it; the AT&T/T-Mobile one uses a sligtly different Intel chip. The Qualcomm one is both newer and faster than the Intel one.

MORE: It takes dozens of companies to make your iPhone

Still, analysts told Bloomberg — it’s straight up weird for a technology company to throttle itself in this way. But that brings us back to the top, and most consumers’ (and developers!) assumption that an iPhone is an iPhone is an iPhone.

“They don’t want one version to get the reputation that it is better,” one analyst told Bloomberg. “If Apple had a guiding principle, it’s that they want to make sure customers were having a consistent performance.”

Other analysts pointed out that not only does Apple need to create a unified customer experience, but also will want to keep all wireless carriers equally happy.

“Apple likely has some incentive to balance the performance of its iPhones across its U.S. operator partners,” a different expert told Bloomberg. “It would be difficult, for example, to explain to AT&T, which remains the U.S. carrier with the most iPhone subscribers, why Verizon is offering a superior product.”

Apple Chip Choices May Leave Some IPhone Users in Slow Lane [Bloomberg]

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