Ancient Rome 37-order by serva

the servant girl on the right order the slave girl how bring food in the hall. The slave girl pays attention to servant's words.
We can see the difference between the two: the servant (or probably she is a high level slave) is covered by a blue tunic; the slavegirl has a heavy collar with a plate, a skirt and two gold pieces of metal over nipples.
I think is very humiliating for a slave to be ordered by other servant or slave