Denotation is the literal definition of the word, while connotation is the social context of the word. Using the contrast between denotation and connotation can be a great way to convey certain attitudes and ideas. For instance, the word mother usually has a strong connotation. Most people think of a mother as much more than just a woman who has given birth to children. You could use the connotation of the word to stress the value of a mother or the positive feelings this word brings to many of us. You could also go against the usual connotation and say that a particular mother was not much more than the denotation suggests. The specifics of the comparison and contrast will depend on the idea you are attempting to convey and the audience you wish to convey it to.