The more informal kind of Buddhism, as opposed to the strict and formal Theravada Buddhism. Mahayana literally means big ox cart, while Theravada means small ox cart, because there are many more people who are informal than formal. Some believe in the teachings and ways of Buddha but do not follow and believe all of them. Many Mahayana Buddhists are atheists and do not see Siddhartha Gautama as a God, but rather a teacher to look up to. However, a Mahayana Buddhist isn't necessarily atheistic, just not as strict as Theravada Buddhists.
Example for Mahayana Buddhism:
I'm a Mahayana Buddhist, and although I believe in everything Buddha taught in his lifetime, I do not consider him divine or godly.