To distinguish between "want" and "wish" is typically easy, but parsing between "desire" and "pleasure," or "obligation" and "commitment," reveals a profound distinction: your motivation and expectation.
For instance: An obligation is something you must do whether you want to or not. A commitment is a promise you keep out of a sense of honor. You are "obligated" to go to work tomorrow. You "commit" when you say your wedding vows.
For instance: "Desire" is a compulsion to seek. "Pleasure" is finding enjoyment in the present.