Use words/terms/phrases/expressions 6

An aficionado is someone who is very interested or knowledgeable about a particular subject or activity. 
Sample:  She is an aficionado of fine food. 

An expert who knows what he is admiring.

A connoisseur is someone who knows a lot about something such as art, food or music. 
Sample:  He is a connoiseur of fine dining. 

http://www.dictionary.com/ provides another two definitions which are useful:

A connoisseur is...
1. a person who is especially competent to pass critical judgments in an art, particularly one of the fine arts, or in matters of taste: a connoisseur of modern art.


2. a discerning judge of the best in any field: a connoisseur of horses.