Makruh means that which the Lawgiver asks us not to do, but not in a definitive manner. Haram means that which the Lawgiver requires us not to do, in a definitive manner.

Haram in Islam is that for which the one who does it may be punished and the one who abstains from it will be rewarded. Halal in Islam is that in which there is no sin in doing it and no sin in not doing it.