Coding Ambulation

I need to know when to code 781.2 for ambulation dysfunction vs. 719.7 for Difficulty walking? I know there's a difference but I'm having difficulty finding a definitive code or definition of each.

re: Coding Ambulation

Abnormality of gait (code 781.2): It is appropriate to report code 781.2 for patients who have gait disturbances without identified cause (ex, joint disorder).

However, if documentation supports the difficulty in walking was due to a joint disorder, code 719.7.--- Other and unspecified disorders of joint 719