The Neural Engine exists because matrix math for inference is wasteful on a general CPU if you do it all day. Apple exposes it through CoreML: a model is converted, compiled for the chip, and scheduled by the OS. For dictation that means a local recognizer can keep real-time factor under one without spinning up a data-center GPU. Battery and fan noise improve when the work stays on the accelerator. The first run may compile the model, which is why the initial dictation can feel slower than the tenth.
Not every on-device app uses the Neural Engine well. Some fall back to CPU if the model format is wrong, if the conversion failed, or if the process is sandboxed away from the accelerator. Intel Macs have no Neural Engine, which is why some Mac dictation tools require Apple silicon. On a Windows laptop the equivalent story is CPU cores or an NVIDIA GPU, not the ANE. When a spec sheet says 'Neural Engine,' read it as a Mac performance note, not as a feature Windows users are missing in name only.