Put simply, plot is the sequence of events in a given story. It is often divided into five parts, as in Freytag's pyramid. The first part, "Exposition," introduces the main characters, the setting and any necessary background information. The second part, "Rising Action," introduces the central conflict, the problem which will drive subsequent events. This culminates in the third part, "Climax," in which the central conflict comes to a crisis point. The final two parts, "Falling Action" and "Denouement," portray the aftermath of the crisis and conclude the story.
The setting is the time and place in which a story's events occur. For example, the setting of Shakespeare's "Romeo and Juliet" is Verona, Italy, during the Italian Renaissance. Depending on the author's approach, setting can be very minimal, as in Beckett's "Waiting For Godot," or very rich and detailed, as in Melville's "Moby Dick." It provides the general context through which the reader understands the events of the story, and can even become a character in its own right, as Prospero's island does in Shakespeare's "The Tempest."
Tone is a function of authorial voice and refers generally to the author's attitude toward his subject. For example, Tom Wolfe's novels have a consistently satiric tone, while the works of Cormac McCarthy are known for their dark, brooding tone. While a story's individual scenes may have their own mood, tone is the dominant mood of the story as a whole.
Style is similar to tone but has more to do with the way an author actually writes rather than his attitude toward the subject. Word choice, use of grammar, syntax and characteristic phrasing and imagery are all elements of an individual author's style. Unlike tone, an author's distinctive style can usually be seen in all of his stories. It is an effect of the way an author approaches writing as a craft, rather than of his attitude toward a given subject.
Point of view is the perspective from which a story is told. Stories written in the first-person point of view are told by a character within the story. For example, Ishmael, the protagonist of "Moby Dick," is also the novel's narrator. The second-person voice -- in which the narrator refers to the reader as a character in the story -- is rarely used in fiction. For example, "you get some cheesecake from the refrigerator" is second-person voice. In the third-person voice, the narrator removes herself from the story completely, referring to all characters using third-person pronouns (he, she, it and they). The majority of works of fiction are written in this point of view.
Characters are the individuals populating the world of the story. They are usually human, but can also be non-human beings, as seen in genres like science fiction or horror. The main character is known as the protagonist, while his primary opponent is known as the antagonist. These are generally the most well-developed characters in a given story. Less well-developed characters are often referred to as "minor" characters, and, depending on the writer's needs, can perform a variety of functions within a story.
Theme -- sometimes referred to colloquially as "the moral of the story" -- is the overall message or idea that a story attempts to convey. For example, an important theme of Harper Lee's "To Kill A Mockingbird" is the existence and impact of social inequality. The theme of a given story is rarely stated outright, except in the cases of fable and allegory. While a writer has a great deal of control over thematic concerns and the way they are portrayed, theme is just as much a function of the reader's sensibilities. No two people will understand a story's theme in exactly the same way.