Both Buddhism and Jainism. have many similarities and dissimilarities. As remarked be Monier Williams.
"Buddhism and Jainism were not related to each other as parent or child but rather children of common parent, born at different intervals, though at about the same period of time and marked by distinct characteristics, though possession a strong family of resemblances". W.W. Hunter writes "Jainism is as much independent from other sects, specially from Buddhism as can be expected, from any other sect.
Not withstanding certain similarities, it differ from Buddhism in its ritual and objects of workship."
(1) The source of both the religion is vedic religion and both and indebted to Upanishads
(2) Both Gautam Buddha and Mahavir belonged to princely families and not to priestly families.
(3) Both deny the existence of God.
(4) Both denied the authority of the Vedas and the necessity of performing sacrifices and rituals.
(5) Both have accepted the theories of Karma rebirth and Moksha.
(6) Both taught in the language of the common people i.e. Prakrit and not in Sanskrit which was the language of the priests.
(7) Both of them were opposed to animal sacrifices.
(8) Both of them admitted disciples from all the castes and from both sexes.
(9) Ahimsa is the prominent principle of both the religions.
(10) Both Buddhism and Jainism put stress on right conduct and right knowledge and not on religious ceremonial and ritual as the way to obtain salvation.
(11) Both, the religions came as a sort of reform of Hindu religion.
(12) Both the Religions were later on divided into two sects. Buddhism was divided into Mahayana and Hinayana. Jainism was divided into Svetambara and Digambara.
(13) Both had their own three gems or 'Tri Ratna'. Tri Ratna of Jainism were right philosophy right knowledge and right character. The Tri-Ratna of Buddhism were Budhha, Dhamma and Sangha.
(14) Both had three main religious texts. Tripitaka, i.e. Vinaypitak, Suttapitaka and Abidhamma pitak were the three religious texts of Buddhism, where as Anga i.e, Anga, Upanga and Mulgrajitha were those of the Jainism.
(1) Difference regarding conception Moksha :
According to Buddhism, a man attains Moksha when he ends all the desires and can attain it while living in the world. But according, to Jainism Moksha is freedom from miseries and can be attained only after death.
(2) Means of attainment of Moksha:
According to Buddhist Sangha is proper for attainment of Moksha and they hate self-mortifications and severe penances. Jainism believes in fasts and severest penances.
(3) Ahimsa :
Though both emphasise the principle of Ahimsa, yet Jainism is more strict in this connection.
Buddhists do not believe in the existence of soul whereas Jainism believes the existence of soul in every living being.
(5) Regarding Conduct:
Buddhism emphasises the eight noble piths whereas Jainism emphasises Tri Ratna.
(6) Language of Religious texts :
Most of the Jain texts are in Sanskrit and Prakrit whereas Buddhist text are in Pali.
(7)Their connection with Hinduism : Jain religion is nearer to Hinduism whereas Buddhism followed the policy of keeping away from Hinduism.
(8) Caste system :
Jains opposed it but Buddhism opposed and attacked vehemently.
(9) Royal support and patronage :
Buddhism received the royal support and patronage of kings like Ashoka and Kanishka. But Jainism could never receive strong royal support and Patronage.
(10) Propagation :
Buddhism spread to foreign countries whereas Jainism did not travel outside the boundaries of India.