A couple consists of
Two equal and opposite forces acting on a body in the same line
Two equal, opposite and non-collinear forces acting on a body
Two equal, forces acting on a body in the same direction
Two unequal, forces acting on a body in the opposite direction
A couple is defined as 2 equal and opposite forces which act in a different line and contributes to rotation of the body in a certain direction.
The two forces equal in magnitude but acting opposite in direction on a body are called unbalanced forces.
Two forces that are equal in magnitude are acting on a body in opposite directions along the same line of action cancel out each other.