It is not uncommon today for businesses and individuals to commission a piece of art. What would you argue is the greatest benefit to an artist of working for a commission?

the correct answer would be "the amiens cathedral"

i believe the answer is  the similarity is that both are sacrifices which have the same purpose and sacrifice - jesus christ, but the difference is in offering of that sacrifice.

the similarity is that both are sacrifices which have the same purpose (repenting our sins) and sacrifice - jesus christ.  the difference is in the way of the offering that sacrifice. the sacrifice of jesus on the calvary is sacrifice of his actual living body and blood, but the sacrifice of the mass is the sacrifice of the jesus through bread (body) and blood (wine). in the sacrifice on calvary jesus was offered for us; while at mass he offers himself through us.