Pencil Pro or Pencil (USB-C)
Apple Pencil Pro is the fuller stylus: pressure and tilt sensitivity, a squeeze gesture to change tools, haptic feedback, and Find My so you can locate it when it rolls off a desk. It charges and pairs magnetically on the side of a supported iPad.
Apple Pencil (USB-C) is the simpler one. It does tilt but not pressure, has no squeeze gesture and no Find My, and it charges over a USB-C cable. It attaches magnetically for storage but does not charge that way.
For note-taking and marking up documents, the USB-C Pencil is enough. For drawing and painting, pressure sensitivity is the whole point and the Pro is the one to buy.
Neither choice matters if your iPad does not support the one you want - check first.