Answer:
Auto Mode--The camera chooses the settings for your photo, which is a good idea if you have no clue what settings to use. Auto mode works well when there is good lighting, but it may struggle when the lighting is uneven.
Portrait Mode--The camera will "think" that there is an object in the foreground to focus on, so it has a shallow depth to keep the focus on the object and blurs the background.
Sports mode--The camera takes the picture in only a fraction of the time it takes pictures in any other mode, because sports are fast activities. Flash is not usually necessary because of high shutter speed used to freeze movement.