Clustered index exists as sorted row on disk.

Clustered index re-orders the table record.

Clustered index contains record in the leaf level of the B-tree.

There can be only one Clustered index possible in a table.

Non-clustered is the index in which logical order doesn’t match with physical order of stored data on disk.

Non-clustered index contains index key to the table records in the leaf level.

There can be one or more Non-clustered indexes in a table.