What is the difference between Uniswap v3 and V4?

I'm curious to understand the key differences between Uniswap v3 and the upcoming V4. Could you elaborate on the enhancements or changes that V4 brings to the table? Specifically, how do the features, functionality, and potentially, the user experience differ between the two versions? Additionally, what impact do you anticipate these changes will have on traders, liquidity providers, and the overall DeFi ecosystem?