What are the differences and similarities between Sikhism and Hinduism?
Hinduism being here longer is more morphus, and is less walled and concretely defined, thus hard to argue which practises are part of core Hinduism - they vary based on which tradition of Hinduism one follows. Sikhism being a young religion, and very concretely defined by the gurus - the only definition comes from Guru Granth Sahib - the Sikh scripture, which is considered the only and everlasting Guru. There have been a rise in number of other tradition claiming anywhere on the spectrum between Hinduism and Sikhism, but Guru Granth being the gold standards debunks, thus none of the traditions other than Guru Granth Sahib, which is essentially written knowledge - can claim any authority on Sikhism.
- Both originated in South East Asia.
- There is emphasis in both about being one with and taking care of the environment. Symbolism of earth as mother, air as life giver are common in both.
- Emphasis of hard work and not the fruit is common in both (Bhagwad Gita/ three pillars of Sikhism).
- The stories of Indian Epics Ramayana, Mahabharata are used in both. However unlike Hinduism where Rama is a God, in Sikh scriptures, his name when used as a reference to Lord Ram is as a contextual character, and not as a God (Many Hindutva pushers try to push the opposite to build a connection which there is not).
- The status of those who remember God is supreme in both over kings. The difference however is that in Hinduism Brahmin is by birth.
- The status of women was pretty elevated in Sikhism and in ancient Hinduism, less so in later periods.
- Sikhism debunks many practises of Hinduism (as well as Islam). These include existence of trio - Shiva, Brahma, Vishnu, idol worship, ritualistic practises, or authority by birth(e.g. that of brahmin or other class).
- Sikhism is monotheistic - believes in one God, which has been referred to many names - Ram, Allah are both names referred in Guru Granth Sahib.
- Sikhism neither encourages, nor discourages neither feels threatened of conversions. The four open doors (for people of four corners of the world) of Darbar Sahib Amritsar signify that.
- One of the cores for which Guru Teg Bahadur gave his life was to defend dignified choice for all. In this case it was for Kashmiri Pandits to practise Hinduism in tyrannical Mughal empire. If it was the opposite, Sikhism preaches to follow same path.
- Sikhism has no room for caste system. Everyone eat together in the same Langar.
And there are more. For a Primer in Sikhism, I would suggest The Sikhs by Patwant Singh. For Hinduism good primer English are books by Eknath Wishwaran e.g. The Upanishads (Classic of Indian Spirituality)