ASTRONAUT (english speaking nation) OR A COSMONAUT (Russian):
An astronaut or cosmonaut is a person trained in a space program to be a commander, pilot, Mission specialists , payload specialists, Payload commander or any crew of a spacecraft. They include people from various professions such as Engineers, doctors, etc who are especially trained by NASA to go on a spaceflight.
NASA gave the title 'Astronaut ' to a crew member on a spacecraft, traveling to earth orbit or beyond or those who are selected for Astronaut Corps.
The rocket engineers are scientists who are aerospace engineers who specialize in design and manufacturing of spacecrafts. great examples of such engineer is Werner Von Braun, Robert Goddard, etc.
Flight director has overall operational responsibility for missions and payload operations for all missions. This person manages other flight controllers remaining in constant communication as in Gene Krantz