They can be very similar, but in general ‘modesty’ talks about what you display or present to the outside world, whereas ‘humility’ deals with your own core beliefs. For example, someone who doesn’t show off his wealth by buying expensive things is being modest. But an adherent of a religion feels humble before God.

Modesty requires some humility. But essentially, modesty is knowing that you have limitations, accepting those limitations, and not trying to exceed them. Humility is knowing that you have status, but lowering yourself and raising other people’s status, even above yours in many cases.