Gross is the discount that is overall total discount that seller is giving. Net is the discount that goes totally to buyer. Remaining is divided equally among both sides as a commission.

i.e -4 gross meaning total 4% discount and 2% net means from 4% there will be 2% for buyer and remaining 2% will be divided equally like 1% for sellerr side intermediates and 1% for seller side intermediate.

Hope you got the answer