A USB camera module is a tiny camera that already speaks the host's language. Plug it in, UVC enumerates, a laptop or a medical PC sees a webcam. That is why USB 2.0 is still a shop category, not a museum piece. The old pages mixed '4K' with 'Sony lens' and hoped. Here is the honest version.
USB 2.0 is a pipe
USB 2.0 has a useful ceiling. MJPEG or YUV at modest resolution is its job. A 48 MP sensor on USB 2.0 is a burst or a scaled stream, not a lossless 4K RAW pipe. If you need that, you wanted USB 3 or MIPI. We still build USB 2.0 because kiosks, industry PCs, and carts still have those ports. See USB camera modules.
What 4K means here
4K in this shop is usually a high-resolution CMOS (for example IMX586) plus a lens that can still resolve it, wrapped as UVC. Example: 48MP IMX586 USB camera. You buy detail for document, inspection, and content, and you accept that the ISP and the USB payload are part of the picture. If the lens is mush at Nyquist, you bought a smoother 48 MP blur.
How to choose
- PC or existing software: USB / UVC.
- Automotive USB with a known sensor family: AR0230 automotive-grade USB camera.
- Embedded SoC, low power, RAW: step over to MIPI instead of forcing UVC.