Evaluating Expressions -(x-y) =-x+y : Are they equivalent

Is -(x-y) = -x+y ? Answer the following : (a) If x and y are substituted with different values as shown above and the expression on the left of "=" and expression on the right are evaluated, do they have the same result? (b) If yes, can we say that -(x-y) = -x+y ?