ironic distance
'Ironic distance' is the disparity between what a narrator knows and what a character says/does. For example, the narrator will often know that a character is acting on a particular impulse out of spite, whereas the character believes something else. So Clifford is really vengeful when he learns about Constance's affair, but he believes he is acting in the name of morality. The narrator's description of what Clifford believes is his moral sensibility shows that he is treating the impulse ironically.
verbal irony
'Verbal irony' occurs when a character says something and means something else. An example of this occurs when Constance is having a conversation with Clifford about the possibility of bearing a child. She says that it would not make a difference to her in her affection towards him if she had an affair with another, but the narrator tells us that she does not really mean this.
dramatic irony
'Dramatic irony' occurs when a character acts on knowledge or articulates something which the reader knows to be untrue. An example of this occurs when Tommy Dukes articulates the idea of the "penis and the belly" being the guiding forces in life in an intellectual conversation. By the very act of his turning this into an idea and talking about it in a philosophical conversation, he is contradicting himself.
situational irony
'Situational irony' occurs when a narrative creates expectations due to the circumstances in a story and then does not fulfill these expectations. An example of this occurs in Constance Chatterley's name. She is not "constant" at all, but rather is unfaithful to her husband and is generally a changing person.
