What is the difference between a Cluster and a Non-Clustered Index?

What is the difference between a Cluster and a Non-Clustered Index?

Approach: Compare physical storage order vs logical pointers.

A clustered index defines the physical order of data in the table. A non-clustered index is a separate structure that contains pointers to the physical data rows.

Follow-up: How many clustered indexes can a table have?

Key concepts: disk storage, leaf nodes.