What are the key differences between SPX and ES?

The key differences between SPX and ES are that SPX is the symbol for the SP 500 index, which represents 500 large-cap U.S. companies, while ES is the symbol for E-mini SP 500 futures contract, which is a derivative financial instrument based on the SP 500 index. SPX is an index that tracks the performance of the underlying stocks, while ES is a futures contract that allows investors to speculate on the future price movements of the index.