Let's create some definitions

Member(s) of Congress (MOC) DEFINITION

A Member of Congress (MOC) is a person who has been appointed or elected and inducted into an official body called a congress. In the United States the word Congress is used as a descriptive term for the collective body of legislators, from both houses of its federal legislature: the Senate and the House of Representatives. 

In order to distinguish who is a member of which house, a member of the Senate is typically referred to as Senator, and a member of the House of Representatives is usually referred to as Congressman/Congresswoman, or Representative. Although Senators are members of Congress, they are not normally referred to or addressed as "Congressmen" or "Congresswomen" or "Congresspeople".