Face Detection is a stage whereby you search for a photo to find any face, and then the image is processed to enable the facial image to be recognized.
Face Recognition involves the area of the detected and processed face in comparison to a database of well known faces, to figure out who the person is.
Face recognition department has been very active in the computer Vision and Biometrics industry, as it has been under study for the past 25years and it has in the long run produced applications in sectors such as digital cameras, security, human computer interfaces and entertainment.
From the year 2002, Face Detection has been working quite well such as with use of Open CVs Face Detector, performing on approximately 90-95% of clear photos of an individual looking straight at the camera. It is normally harder to detect an individual's face when they are inspected from an angle or while at the side, and in other times this needs 3D Head Pose Estimation. It can be quite hard to detect an individual's face if it is not bright enough, or part of the persons face is brighter than the other parts, has shadows, and has blurriness or if the person is wearing glasses.
Nonetheless, Face Recognition is not that reliable compared to Face Detection, approximately 30-70% accurate. Face Recognition has been a major field of study since the 1990s, though not 100% reliable, more and more advancements are being made every year.