Proportions.
Buyer. "In future, as my collection increases, and my wall-space is limited, and price no object, perhaps you would let me have a little more 'picture,' and a little less 'mount'!"
Buyer. "In future, as my collection increases, and my wall-space is limited, and price no object, perhaps you would let me have a little more 'picture,' and a little less 'mount'!"