Higher amount of calcium deposits?

The relative salinity of the two oceans varies with latitude and season.At certain times areas of the Atlantic have a lower salinity than some areas of the Pacific.
The factors which affect salinity are evaporation rates,temperature,and rainfall = fresh-water inputs.
The vaste expanse of the Pacific straddling the equator and the tropical rainfall associated with this compared to the much narrower region of the Atlantic in the same latitude may account for the slight variation.

The Pacific ocean is higher than the Atlantic ocean because the Atlantic ocean is warmer, hence saltier, hence more dense, and being so heavy, it is lower. Water flows from the Pacific to the Atlantic in the Panama canal. This was actually an environmental concern when the canal was built and a series of locks prevents too much flora and fauna from going through.