Both comprehension and understanding can be used to talk about someone's ability to understand something. The meaning of understanding is a mental grasp : Comprehension usually used with of.
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He noted bond's apparent lack of. Knowledge about a subject, situation, etc. Mental process of a person who comprehends;
Understanding implies abilities and dispositions with respect to an object.
Understanding is a relation between the knower and an object of understanding. Or about how something works: How to use understanding in a sentence.
