RIGID DIAPHRAGM - DIFFERENCE FLOOR DIAPHRAGM AND MASTER SLAVE

I develop simple model 1 story structure consist of slab and column only (no beam). Then I apply vertical load on the middle of the slab.

After that I put rigid diaphragm using master slave and run the model. As the result, I got all support reaction at every column is exactly same.

Contrary, when I'm using floor diaphragm, the supports reaction are different for each column. Column near applied point load have higher reaction.

My question, why the result different? Manual said that both method can be used. So, what condition suppose master slave or floor diaphragm to be used? 

Thank you for the answer.