Deities, such as the one's found within Hinduism, to the Buddhist, do exist, but are trapped in the cycle of samsara like we are. They are a bit more evolved spiritually, and can on occasion even offer a little help, but none can save us, none can offer us enlightenment, none can purge our unwholesome karma. You won't actually find many Buddhists praying to the deities.
Now, we have a plethora of Buddhas and bodhisattvas that are seen as higher than the gods, and are often given veneration and devotion. Beings such as Amitabha and Avalokitesvara are venerated and invoked. However, the general understanding is that these beings are not "gods" in the traditional sense, and are Buddhists who have reached higher states of enlightenment, who can offer their assistance to us on our path. And some, like myself and many Zen Buddhists, don't even see the external-ness of these beings as being important, but that these beings are a part of our minds, and this is their main importance, i.e., when we invoke Avalokitesvara, we're not invoking a being "out there", but the ultimate compassion in our own minds.