After simplying the following expressions, which one is different from others? 
Overseas Competition->Knowledge Point->Calculation Modules->Basic Concepts of Equation->Equivalent Substitution->Algebraic Expressions
$(x+y)-(x-y)=2y$  $(2x+3y)+(-2x-y)=2x+3y-2x-y=2y$  $(3x-2y)+(-3x+4y)=3x-2y-3x+4y=2y$  $(x-y)+(-x+y)=x-y-x+y=0$ 