Income ceiling means some kind of limit being set for income. A person might not be allowed to earn more than a maximum fixed amount.

The glass ceiling is a social phenomenon. That is, women (or Asians, or Blacks, or whichever minority group you are talking about) can't get beyond a certain level in the social hierarchy. The income ceiling is not really a social phenomenon, simply financial. That is there are no teachers in North America that earn more that X $. That would be their income ceiling. There are no ambulance drivers that earn more than X $. So, I believe, an income ceiling is associated with a particular job or skill set.