Well I usually use market to put high price offers for the items I am trying to sell, in order not the devalue them, if I am not in a hurry to sell.
On the other hand, I usually use advertising to announce those same items without price, accepting offers with the minimum amount of cash I want to get for them.
For example, I got toga motis in market for selling at 17kk, I already sold in the last weeks 2 of them in that price for market. But in advertising I accept offers of 14kk by trading them.
Advertising Is also useful to change one item for other, who knows maybe somebody does not have the cash I am asking for, but they got Items in exchange that could be useful for me.