The term "parable" usually refers to a short story or object lesson that is used to explain or teach a moral truth. It can also refer to a saying that is difficult to understand and about which the hearer will have to think carefully before he can understand what the speaker is teaching.
* The story of the Good Samaritan is an example of a parable that is a story. Jesus' comparison of old and new wineskins is an example of a parable that was an object lesson to help the disciples understand Jesus' teachings.
* A "riddle" is a type of "hard question." The one who asks a hard question does not know the correct answer, but he hopes the hearer can answer correctly. The one who asks a riddle does not want the hearer to be able to answer the question correctly.