Difference between Ulutan and Hackfight?

Hackfight: Owners of chicken ask for the opponent chicken to fight. But must be the same weight.
Ulutan: Same weight of chicken pairing together to fight.
What is the difference?
This is strange. In Tagalog, "ulutan" means "pairing", right? But they also pair chicken in derby by weight, so where is the difference?
Help me here, guys. I am not from Philippines so I can't possibly know the answer since most of the articles are written in Tagalog.:confused: