Can aerospace engineer be an aeronautical engineer?

Yes, an aerospace engineer can be an aeronautical engineer, as aeronautics is a subfield of aerospace engineering focused specifically on the design and development of aircraft. Aerospace engineering encompasses both aeronautics (aircraft) and astronautics (spacecraft). Many aerospace engineers may choose to specialize in aeronautics, applying their skills and knowledge to aviation-related projects. Thus, the two disciplines are closely related, and professionals can transition between them.