MacRumors found the gap on Apple's own technical specifications page. The iPhone 18 Pro lists Apple's C2 modem. The iPhone 18 Pro Max lists no modem at all, and the same thing shows up on Apple's announcement page for the two phones. The band lists differ too, with Band 106 on the US Pro sheet and no Band 106 on the Pro Max sheet. Both phones do share N1, Apple's own networking chip for Wi-Fi 7, Bluetooth 6 and Thread.

Apple hasn't explained the difference, and rumors before the launch had some iPhone 18 models staying on Qualcomm modems. Apple is using C2 in the iPhone Duo as well, so supply is one available explanation. What Apple does say about C2 is that it covers sub-6GHz and mmWave 5G and is faster and more energy efficient than the C1X. It has not named what is in the Pro Max, so there is nothing to compare it against. Both phones go on sale September 18, and they are closer than usual elsewhere: both got the variable-aperture main camera, not just the Max.