All these will tend to create inner tension. Or it may come out as laughter. If two people come together they may regard their differences as something to be serious about or to be angry about, or, on the other hand, they may regard them as material for light-hearted humour. Friendship, which can easily be between individuals with quite different characters, will often have this quality. Each may gently pull the leg of the other, and it causes no ill-feeling, but rather a closeness.
Laughter dissolves barriers harmlessly.
What is true of external systems is true of equivalent internal ones. If I have two sides to myself and each can be amused at the other, they will be friends and live in harmony. If, on the other hand, they are angry with each other, then I am a house divided against itself, and cannot stand. When I find a client who cannot laugh at life, I know that there are going to be problems. Such a person has limited options when it comes to resolving differences between himself and others and between different aspects of himself.