The many images of Buddha are actually Buddhas. The word Buddha means “enlightened one”, and everyone can attain Buddhahood by becoming aware of their Buddha-nature. Siddhartha Gautama is the founder of Buddhism, this is the most common image of Buddha, he is thin and has long ears and is usually making a mudra (hand sign). In different schools of Buddhism there are Boddhattvas, or people who achieved Buddhahood but for one reason or another refrained from entering Nirvana and instead stayed behind. For example there is the story of one Boddhattva that stayed behind until the entire world was enlightened and achieved Buddhahood. Another felt compassion and mercy and stayed behind to help those in need. They are considered Buddhas in their own right. The fat and jolly Buddha is Hotei Buddha in Chinese Buddhism. He is a Boddhattva, a person who achieved Buddhahood but refrained from entering Nirvana. Jizo is another example. He usually bald, somewhat fat, standing holding a stick, and very small. He is usually associated with dying children or children who suffer. It is said he refrained Nirvana for this purpose.