Is there actually any hard data out there comparing the NPU on the Google Tensor G4 vs the Apple A18? I wasn't able to quickly find anything concrete.
I mean Apple has been shipping mobile NPUs for longer than Google (Apple: since A11 in 2017, Google: since 2021), and are built on (ostensibly) a smaller silicon node that Google's (G4: Samsung SF4P vs A18: TSMC N3E). However, the G4 appears to have more RAM bandwidth (68.26 GB/s vs 60 GB/s on A18).
Google has been shipping custom NPUs since the Pixel 4 in 2019. Prior to that, Google phones just used off the shelf SOCs from Qualcomm, with 2018's Pixel 3 using the NPU in the Snapdragon 845. Android first shipped NNAPI in Android 8.1 in 2017, with acceleration on various mobile GPUs and DSPs, including the Pixel Visual Core on the Pixel 2. Google has shipped more on-device models so far, but neither company has a moat for on-device inference.
