Superposition
Superposition is when two waves meet, the overlap and interact. They sometimes add to make a wave bigger. Also at time, they cancel each other out however often it is a combination of both.
Constructive interference
Constructive waves are two or more waves of equal frequency and phase which result in their mutual reinforcement and producing single amplitude which equal to the sum of the amplitudes of the individual waves.
Destructive interference
Destructive interference are two or more waves of equal frequency and opposite phase which result in their cancellation where the negative displacement of one always coincides with the positive displacement of the other.
Node
A node is a point along a standing wave where the wave has minimum amplitude. It is also described as points with no displacement which are located along the medium.