What are the differences between FFEL Consolidation vs. Direct Consolidation?

Borrowers are encouraged to check with their existing loan holders or servicers to find out about consolidation options available to them. Some differences between programs may include:

Minimum balances or numbers of loans required to apply.
Types of loans that can be consolidated.
A prior account relationship may be required.
Repayment incentive benefits to encourage good repayment behavior.
The convenience [...]