Is there really no difference between Vedas and Qur'an since they both teach monotheism , life after death and they are very similar then how to know which to follow ?
The Rigveda pays homage to DEITIES. End of story.
The only similarity between Vedas and Qur'an are the themes of charity, compassion and the shunning of hypocrisy, but you could look to any religious scripture and find these topics.
Believe me, Hinduism is the most confusing and nonsensical religion I have ever heard of, I studied it as part of my degree and I still have no idea how their concept of the afterlife works.
All in all, you cannot liken Dharmic religions to Abrahami