difference
 

what separates an SB from an SC or is it only the letter on the water table

The engraving is different.

Thanks now the hard one, how can I tell? does the pigeon make a difference or certain patterns? I have not seen the gun that I'm going to look at and just need some information so I look like I know what I'm talking about HaHa

A lot. Engraving, checkering, wood quality, markings.

Unless I’m mistaken the pigeon was on the bottom of the later manufacture SC’s .

If you go to the home page and click on Parker grades, you will find pictures of all the grades of sbt guns.

Thanks guys