The Curator is the person in charge of a collection of a museum or the 'temporary collection' of an art gallery. The curator's task involves screening and selecting the collection, documenting and finding ways to make sure this will be preserved and handled well, presented and mounted properly (exhibit design and layout), promoted and marketed to as many people (audiences/visitors) as possible. This authority can also be handled by a group or a team like a curatorial board.
However, there is a gray line that separates the curators who handle museum collections and those with changing exhibitions like in an art gallery. The difference is in the perception of art brokerage, which is the buying and selling of artworks. Museums are not mandated to sell (since their mission is to preserve) while galleries act as brokers between artists, collectors and buyers. The curatorial expertise of an art broker becomes suspect in the light of his role as an art dealer. But this is a wrong perception.
The value judgment and prudence required in ensuring that the best of the community's creative works are preserved whether in a museum setting or in individuals homes stand equal in promoting and protecting one's cultural heritage. The best works of art are not only seen in a museum. And a museum may not always be the best place to preserve important works especially if they do not have the proper resources to do this tedious task. Which is why a lot of important works for retrospective exhibitions are mostly loaned from private collectors sourced at times by art galleries!
Personally, I look at more pressing issues like the exercise of curatorial authority and expertise in matters of taste and artistic/historical merit as more important than the manner of preserving artworks. A curatorial authority is an exercise in value judgment which must be able to pinpoint the genius among all the creative productions and bestow the highest honor and pride in its value. To assert authority in demanding excellence of creative works and to call forth works that are lacking in artistic maturity and merit rather than to give in to bureaucracy, popularity and market demands which only encourages commercial productions and confuses an art market.
The main concern of curators of both museums and art galleries is to encourage people and institutions to collect important works of art and objects and maintain them well. Caring and preserving one's cultural heritage whether these are tangibles (objects) or intangibles (stories, traditions, etc.) should be instilled in an individual because it is in the understanding and appreciation of the best in one's culture that people and communities learn to value and take pride in their identities as a people and as a community and inspire them to pursue more noble goals and ideals.