北上 and 登る: moving north and climbing higher
Compare a traveler heading north along a coastal road with climbing a nearby mountain to distinguish compass direction from upward movement.
北上 uses north as its direction
北上 (ほくじょう) means moving north. The reference is a compass direction, rather than the shape or height of the route.
“旅人は海岸沿いの道を北上した。” says that the traveler headed north along the coastal road. Keep the traveler as the person moving and the coastal road as the route.
登る concerns moving to a higher place
登る (のぼる) means climbing to a higher place. Here, the sentence concerns climbing a mountain rather than movement toward north.
“朝早く起きて近くの山に登った。” says that the speaker got up early in the morning and climbed a nearby mountain. Preserve the time and the nearby mountain without adding a northward direction.
Identify the reference for the direction
北上 is based on north, while 登る is based on height. The character 上 in 北上 does not make the word equivalent to gaining elevation.
North is also distinct from the top of a map display. Read the direction and object stated in the examples, rather than deciding northward movement from the screen layout.
Does heading 北上 along the coastal road establish that the traveler climbed to a higher place?
Show the answer and why
No. It states movement north and gives no change in elevation. Climbing higher is the action described by 登った in the separate mountain example.