After Life
Elves have much knowledge concerning their afterlife because of what they have learned from the Valar who call them to be with them in Valinor. Men on the other hand, never got in touch with the Valar and so do not know what would become of them after life. Men are not "immortal" like the Elves for they were granted the gift of death by Eru, whom the Men only heard as a voice. Melkor appeared to the men in a beautiful shape and promised them knowledge if they allowed him to lead them. He told them that Eru was the darkness that wished to devour them. Melkor later threatened the Men to do his bidding or they would be slain and Eru never spoke to the Men again after granting them death. Eru said that although Men had abandoned him he still saw them as his subjects and so he said he would shorten their lives in order to let them come to him and see who their true lord was. Men will pass on to the Halls of Mandos after death but they will not be there long and their fate after Mandos is unknown. Men leave this world after death.
The elves see themselves as two separate parts that are not bound to each other, the Fea and the Hroa. The Fea is the spirit and the Hroa is the body. The Fea is powerless without the Hroa and the body would die without the Fea. The Elves' fates are to live as long as the world exists, elves are bound to the world and cannot leave. Elves are not like Men, Elves do not die of disease and do not grow old. However, Elves may be slain or lose the will to live, for instance because of grief. When an elf dies, the Fea leaves the Hroa which will then be pass on to the Halls of Mandos. The Fea may then choose to be reincarnated into a new-born body that is identical to the previous Hroa. A Fea who chooses to be reincarnated will be reborn a child. The Fea remembers its previous life as its experience and knowledge grows, this the Fea is enriched with memories from two lives. Or, the Fea may decide to stay in Mandos. Should the Fea choose to be reincarnated, the Fea may have to wait a certain period of time depending on the Fea's previous life. If much evil was done by the Fea then the wait would be longer before returning to life. If the evil done by the Fea was to great then the Fea would never be allowed to leave Mandos. The Elves who stay in Mandos, whether or not by choice, are obliged to stay in Mandos till the end of time. Rarely has a Fea been reincarnated more than once.