To catch a glimpse means to see something very briefly. For example if you are in a jungle and you see a tiger for a very short moment - maybe not even the hole tiger. Then you caught a glimpse of it. Or you glimpsed it if you want to use it as a verb. Whereas glance is used, for example if you are waiting for the bus for a short moment and you have a newspaper with you. Then you may say: "I glanced at the headlines while waiting for the bus." Short summary: In the case of glimpse it is the object which appears before your eyes. I use it if I saw something by accident. In the case of glance it is you, or your eyes which go to the object. I use it if I want to see something (not by accident).