Human Act vs. Act of Man

My class has been given another assignment and this time it's about human act and act of man. You know, the cliches, define and differentiate. I've already had my answers but I believe I still don't fully understand the concept of the two. Please do enlighten me since all I can think right now is that the two almost has no difference aside from how they are worded... Thanks in advance! Happy MyLotting!