Write a paragraph explaining the differences between early Vedic religion and classical Hinduism. What changed with this development and what remained the same?

I am looking for someone to write a basic overview of the differences between early Vedic religion and classical Hinduism. The focus should be on the differences between the two, but I would like it to also mention any key changes and similarities. No references or sources are needed. This should provide the reader with a basic understanding of the topic.