## As adjectives the difference between **constructive** and **functional**

is that

**constructive** is relating to or causing construction while

**functional** is in good working order.

## As a noun **functional** is

(mathematics) a function that takes a function as its argument; more precisely: a function

*y''=''f''(''x'') whose argument ''x * varies in a space of (real valued, complex valued) functions and whose value belongs to a monodimensional space an example: the definite integration of integrable real functions in a real interval.