A comic book or “pamphlet” is the traditional periodical form most people are familiar with. A comic book can stand on its own or be a part of a series. A series is also sometimes called a “title,” which refers to the entire series, not a single, discrete unit.
Sometimes, multiple issues of a series are collected into one volume. It can be hardcover (as shown here) or softcover. Softcover editions are often called “trade paperbacks,” or just “trades,” regardless of size. A hardcover or a softcover can also be called a “graphic novel.”
When a story is published in the hardcover or soft cover format first (that is, without periodical serialization), it is referred to as a graphic novel and only a graphic novel.
Many of these terms are inter-changeable, as you can see. A “graphic novel” can refer to a hardcover or soft cover, to a reprint collection or an original story. Similarly, all of the formats referenced can be called “comics” or “comic books.”