Difference Between KFF and DFF

Key Flexfield	Descriptive Flexfield
A Key Flexfield as the name suggest is a key building block of a module and is required for defining the structure of objects of that module e.g. The Account Structure, Item Structure etc.	A descriptive Flexfield as the name suggests helps more in describing an object (like a transaction or screen) more than the available fields on that screen
Key Flexfield captures mandatory business information like company department, account etc.	Descriptive Flexfield captures additional business information like name of the company’s MD etc.
KFF is Mandatory	DFF is optional
KFF displays like text item	DFF displays like []
KFF’s data are stored in the segments	DFF’s data are stored in the attributes
30 segment columns are reserved for KFF’s data	15 attribute columns are reserved for the DFF’s data.