Your understanding might be that your mother will always drive you to school if you miss the bus. Understanding is a relation between the knower and an object of understanding. Or about how something works:
Why C? by Dr Milan Milanović
Both comprehension and understanding can be used to talk about someone's ability to understand something. How to use understanding in a sentence. Knowledge about a subject, situation, etc.
He noted bond's apparent lack of.
Understanding implies abilities and dispositions with respect to an object. Comprehension usually used with of. The meaning of understanding is a mental grasp : Understanding a concept means you get it.