Quick answer: Changbai, Baekdu and Paektu refer to the same mountain system; for China-side trip planning, search primarily for Changbai Mountain / 长白山.
Changbai Mountain
Changbai Mountain is the common English rendering of the Chinese name 长白山 and is widely used for tourism on the Chinese side.
Baekdu and Paektu
Baekdu Mountain and Paektu Mountain are romanized forms associated with the Korean name 백두산 / 白頭山.
The names overlap geographically
They refer to the same volcanic mountain system, but travel terminology, borders and political or cultural context can affect how a specific source describes the area.
For travel searches
When planning a trip on the Chinese side, “Changbai Mountain” and “长白山” are generally the most useful search terms for transport, hotels and scenic-area information.
Editorial note: ticketing, scenic-area access and transport procedures can change. Verify time-sensitive details with current official Changbai Mountain tourism notices before travel.