SQL and Excel serve different purposes: SQL, developed in the 1970s, is a query language for managing relational databases, while Excel, created in 1994, is a spreadsheet tool for data organization and visualization. SQL is essential for handling large datasets without performance issues, whereas Excel is beneficial for quick calculations and data summaries but can slow down with extensive data. Security-wise, SQL offers encryption and access control features, whereas Excel lacks such protections for sensitive data.