Image search tools try to locate pages that contain the same or a similar copy of a picture. They are a good first step when checking a product photo, a news image or a reposted personal picture. Many offer a free initial check.
Face search compares the face within an image. It may suggest a different photo of the same person taken at another time. That broader reach also brings false matches. Results depend on the provider’s indexed public sources and never represent the entire internet.
A practical order is to try image search first for copies of the original picture. If you have the right to use the photo and need a wider check, use face search to explore different images. With either method, open the source link and verify its context.