Difference between Key and Descriptive Flexfield? DFF vs KFF

Key Flexfield(Ex: Accounting Flexfield to uniquely identifies a General Ledger Account.)
1.Unique Identifier
2.Key Flexfield are stored in segment
3.For key flexfield there are flexfield Qualifier and segment Qualifier

Descriptive Flefield
1.To capture extra information
2.Stored in attributes
3.Context-sensitive flexfield is a feature of DFF. (descriptive flexfield)