Before I knew about Buddhism, I always wondered what or who was Amituofo whenever I watched the monks in the TV programme said "阿弥陀佛". Till now, I have friends who are like me. Friends used to ask me who or what is Amituofo.
Heaven is within the 6 rebirth paths. Many Buddhists aspiring to be reborn in Pureland after death. Pureland is not within the 6 rebirth paths. Thus, it is better to be reborn in Pureland than being reborn in heaven. Heaven and hell are only temporary places, they are not permanent. Those who were reborn in heaven will still have a chance to be reborn in animals, ghosts, hell , demi-gods and human realm.
Following is a course introducing Pure Land Buddhism : Understanding
Amituofo Via The Amitabha Sutra.