How does a collection differ from a SQL table?

The difference is that a collection is more flexible and doesn't require a strict schema, while a table has a rigidly fixed structure.

#The key differences

1. Schema

• An SQL table requires columns and their types to be described upfront.
• A MongoDB collection requires no schema - documents can have different fields.

2. Data structure

• A table stores flat rows.
• A collection stores documents, which can hold nested objects and arrays.

3. Changing the data

• In SQL, changing the structure requires a migration (ALTER TABLE).
• In MongoDB, you just start writing new fields, old documents stay as they are.

4. Relationships

• SQL uses JOIN to relate tables.
• MongoDB more often stores related data inside a single document (nesting instead of JOIN).

Summary: a collection is a freer, more flexible document store, while a table is a strictly structured system with fixed columns.