NOS = new old stock (still in original wrapper from GM dealer - stored away and never used
POST = 2 door sedan, post model - lots of names for these
These cars have the pillar between the windows, while a hardtop has no 'post' between the windows (not convertibles)
Hardtop does not have the post
Sport coupe = post = 2 door sedan, lots of people call it different things
Click on the following link to see a picture of a 'post car'
http://homepages.udayton.edu/~mertzgea/car12.JPG
Post cars were a lot less common than hardtops - some say they're rarer and like to think they're worth more $
(but hardtops are a good bit more desirable)
The switches in a hardtop operate options just like in a convertible
Power antenna, reverb for stereo, rear defroster, front/rear speakers option and others can have those little chrome switches to operate them (probably a few more i'm not thinking about)