Biomechanics can be a confusing subject, but I always believe in making it simple for clients, people don’t need to know super specific anatomy, but they should know body positioning and how that affects an exercise.
When training your back, using a wider grip with your elbow higher will always recruit more upper back. This applies to pull ups, pull downs, and rows of all kinds.
If you pull your elbow close to your waist, that works the latissimus more, again this applies to all kinds of chin up, pull downs, and rows.
Exercises are not created equally, different exercises have different effects, developing kinesthetic intelligence and knowing which exercises work what muscles is part of the training experience.