What is the difference between Data Import Wizard and Data Loader?

Data Import Wizard: A browser-based tool accessible from Setup. Supports up to 50,000 records. Works for standard objects (Accounts, Contacts, Leads, Solutions, Campaign Members) and custom objects. Handles duplicate matching. Easy to use but limited. Data Loader: A desktop application (Windows/Mac). Supports up to 5 million records per batch. Works on all objects including ones the Import Wizard doesn't support. Supports insert, update, upsert, delete, hard delete, and export. Requires CSV files and field mapping. Supports command-line automation for scheduled jobs. Use Data Import Wizard for simple, smaller imports; use Data Loader for large volumes, complex objects, or automated processes.