How does Buddhism describe God?
For Buddhism, If you define God as someone who created the world, God does not exist.

But if you define the God as someone who is superior to other beings, then god exist.

However, such a god exists only for a period of time, then one day the god will go down to another level (I mean rebirth) as an angel or human.

The Lord Buddha is not a God. 

In Tripitaka, there is a lesson about how the world is created and how god came to exists.