A pig is a domesticated farm animal. It is an omnivorous mammal, a hoofed animal with bristly hair. It has a flat snout so that it can root around in the soil. Pigs are raised for their meat, which can be anything from pork chops to bacon to ribs.
Swine is another word for pig. It is a more formal word for the domesticated animal. Most people do not use this word. There is no difference between swine and pig.