Coca is the name of a shrub, Erythoxylon Coca.
Cacao is the name of a tree, Theobroma Cacao.
Within many Maya dialects spoken throughout Mexico and Central America, the term cacao is often interchangeable with the word chocolate as known today.
Cocoa is the powder made from the cacao bean, which is mashed into a paste then pounded to extract the cocoa butter and pulverized into a dry powder. It is believed the name ‘cocoa’ came about as the result of a misspelling by early English traders.
Cocoa is also modern version of beverage prepared from the above with milk and sugar. It is a beverage prepared from the crushed unexpressed fruit of the theobroma.
Chocolate is referred to the term applied to a confection made from the above with sugar. It is a product of the fruit of the cacao tree. The fruits grow off the main trunk of the tree as pods, similar in size to deflated football. The trees can grow anywhere from 25 to 50 feet tall.
Couverture is a covering chocolate, specially formulated for coating or dipping. It has a higher percentage of cocoa butter than any other sweetened chocolate enabling it to flow easily and form thin, crisp coatings with a mellow flavor.
Chocolate liquor is the liquid or paste produced when cacao beans are roasted and gerund. It is the pure, roasted and refined cacao bean with no ingredients added.
Ganache is chocolate and cream blended together usually used as a filing for chocolate truffles or as filling or glaze for other confections.
A note on terminology
