Siddhartha was raised an orthodox Hindu. But, realized that though he was a Prince in this life, he was not immune to old age, disease and death. And that future lives would see him in the lowest, hardest levels of living as the Wheel of Life continually moves high to low and back.
Therefore, he set out to find a way to escape the Wheel of Coming and Going or Reincarnation. He found Detachment was the key. His Eightfold Path and Four Noble Truths stand as a Testament to his ENLIGHTENMENT. He resides now in the HIGH HEAVENS and no longer has to reincarnate. He has attained MOKSHA...Freedom as SOUL to travel at will the Worlds of GOD for Eternity.
Hinduism in it's pure state, states that SOUL comes into existence in the mineral state, works up thru plant, animal then human states. Starting out as a primative man, then thru countless lives of generating and working off both Good and Bad Karma, SOUL matures into a more perfected being that no longer needs to reincarnate but can enjoy an Eternity as a Co-creator with GOD in the Worlds of Pure Spirit.
Unfortunately, religions get corrupted over time, and Hinduism adopted reincarnating back to animal form, and the caste system and a million different gods. These are corruptions that Buddha did away with. Unfortunately, Buddhism too, got corrupted and many present day Buddhists teach that there is no GOD, no SOUL, no HEAVEN. Such nonsense. Buddha's main goal was for SOUL to attain ENLIGHTENMENT OF GOD and enjoy HEAVEN without having to come back, again and again...MOKSHA.
This is the basis for most of the religions we see today. From Jewish to Christianity and even Muslim. Have a read through, it is the religion which has been plundered for religious ideas by most of the worlds religions.
*Buddhism rejects gods priests, formal rituals and the caste system
*Did not believe in many gods as Hinduism
Similarities-Hindus and Buddhists both believe in if one desires, he is suffering-
and to stop this, you have to stop desiring.