Answer:
Found this off of google, "Unlike the Healing Brush, the Spot Healing Brush doesn't require you to specify a sample spot. The Spot Healing Brush automatically samples from around the retouched area. Note: For retouching a large area or for more control over the source sampling, you can use the Healing Brush instead of the Spot Healing Brush."
Hope this helps, have a great day and stay safe! :) :D :3