when baking i go for the lower cost chocolates. for eating or praline making i go for the finer chocolates.
the difference is the content and quality of the cocoa solids, cocoa butter, and sugar. the process of conching is most important as well; this is the kneading of the chocolate, refining of the chocolate giving the chocolate a smooth mouth feel and clean break.
couveture is the name of chocolate made with only cocoa mass, cocoa butter, sugar, lecithen and vanilla. No veg shortening or other fats included in couveture, the name of "chocolates" made with other fats is coating.
a fine chcolate is conched 72 hours and your average lower cost chocolate is conched 24 hours. fine couveture needs to be tempered (a series of heating and cooling to melt and bind together the cocoa butter and sugars ) before using while chocolate coating or chocolate made with veg fat does not.
I hope this helps and will answer any other questions you have.
------------------
Thank You,
mb