Who is God, according to The Bible: There is only one God. God is "the Supreme Being; the Creator and Ruler of all that is; the Self-existent one who is perfect in power, goodness, and wisdom." God made the heavens and the earth, created man "in His own image". He is the one we pray to in times of need, in times of thanks, in times of remorse, repent to, and praise in happiness.
Prophet: Jesus, who God sent down to earth to preach His word. Turned water to wine, healed the sick, etc.
Life and Salvation: “For God so loved the world that he gave his one and only Son, that whoever believes in him shall not perish but have eternal life” -John 3:16
Afterlife: Continued existence of the soul in Heaven/Hell.
Islam
Who is God, according to The Qur'an: There is only one God, Allah, which simply means the (al) God (Ilah), deriving form the Hebrew word for God, Elohim. Allah created man using a clot of blood.
Prophet: Muhammed, the last and greatest messengers of God. Not divine.
Life and Salvation: Live life to please Allah so that you may live eternity in Paradise.
Afterlife: Continued existence of the soul in Paradise/Jahannam.
(Chart comparing Christianity and Islam: http://www.religionfacts.com/christianity/charts/christianity_islam.htm)
Hindu
Who is God, according to Vedas/Shruti/Bhagavad Gita/Ramayan: Aspects of the supreme Brahman, avatars of supreme being, or devas.
Prophet: No prophets, just devotion to gods and goddesses: Brahman (god-creator) and his 300,000 reincarneted beings, Vishnu (god-preserver), Shiva (god-destroyer), Saraswati (godess of knowledge), Lakshmi (godess of wealth), Parvati & Shakti (godesses of power).
Life and Salvation: Salvation by works and many reincarnations; Karma's good or bad deeds will determine your chosen afterlife; Meditation.
Afterlife: Samsara, or the cycle of rebirth and death. Good deeds will lead to Svargam (heaven), bad deeds will lead to Narakam (hell), or reincarnation. Good deeds provide you to move to higher sun-filled worlds of reincarnation. Bad deeds will lead to lower worlds and consequence.
Buddhism
Who is God, according to Tipitaka or Sutras: No Supreme Creator, rather Buddha or the Enlightened One. Be thy own refuge.
Prophet: Siddhartha
Life and Salvation: Meditation will lead to Vipassana, or seeing through the mode of impermanence (Side Note: The book Eat Pray Love by Elizabeth Gilbert has a very interesting description of Vipassana).
Afterlife: Samsara, or the cycle of rebirth and death.
The Buddha said of death:
Life is a journey.
Death is a return to earth.
The universe is like an inn.
The passing years are like dust.
Regard this phantom world
As a star at dawn, a bubble in a stream,
A flash of lightning in a summer cloud,
A flickering lamp - a phantom - and a dream.
In Buddhism, there is either reincarnation or Nirvana. Reincarnation is not from one human body to another, but could be to a lower level of being depending on your previous life and how you lived it. Reincarnation is suffering until you reach Nirvana, which can only be achieved by Buddhas:
"It is recognized that there is nothing but what is seen of the mind itself; where, recognizing the nature of the self-mind, one no longer cherishes the dualisms of discrimination; where there is no more thirst nor grasping; where there is no more attachment to external things." -Surangama
(Chart comparing Christianity and Buddhism: http://www.diffen.com/difference/Buddhism_vs_Christianity)
Judaism
Who is God, according to the Tanakh/Torah (or Old Testament of The Bible): There is only one God, Yahweh, or Adonai. Same ideology as Christian God.
Prophet: Abraham, Moses, Miriam, Isaiah, Samuel, Ezekiel, Malachi, Job.
Life and Salvation: Believe in God and perform good deeds throughout life to go to the Garden of Eden (Heaven) or Gehinnom (Hell).
Afterlife: Divine revelation and forgiveness in Heaven, or possibly reincarnation, Gehenna, or no aflterlife at all.
(Chart comparing Christianity and Judaism: http://www.religionfacts.com/christianity/charts/christianity_judaism.htm)
Interesting chart showing the religious percentage around the world.
SIDE NOTE: Mormanism vs. Mainstream Christianity: http://www.religionfacts.com/mormonism/comparison.htm
Just another comparison that shows the differences between the two. I'd say they are just as different as comparing Christianity with all of the above religions.
Jews for Jesus posted this really great chart outlining the differences of Buddhism, Hinduism, Judaism, and Christianity. It's pretty cool to see them all side-by-side: http://jewsforjesus.org/publications/issues/10_4/chart
