Deductions & credits

Can you help me understand the difference between (Partial Section 179 and the special depreciation allowance) and Partial Section 179 by itself?  How would it work if I would take a Partial Section 179 of $10,000 and the special depreciation allowance?  Is the remaining amount after the Partial Section 179 deducted as an expense over the remaining four years or is it depreciated over the remaining four years?  Thank you in advance.