Redneck and Good Old Boy are much the same thing.
Much like Heather I don't really mind redneck, but I don't particularly like the therm "good ol' boy". It's basically become the term used to refer to the often crooked politics of the south, where jobs or public positions are handed out based on who you know rather than how good you are at what you do. IE, Tommy and Billy both apply for a job at the local highway department. Tommy has better education, more experience, etc, but the hiring department manager knows Billy's dad, and he's a "good ol' boy", so he gets the job.
Oh well, rant mode off
.
It kinda just means different things to different people. My brother has an interesting criteria that he breaks it into (he thinks about this type of stuff too much lol). My own opinion is kinda fuzzy but somewhat similar. He insists against being called a redneck. To him rednecks are the odd ones. The toothless, often racist people who tend to have a mean streak and gossip a lot. They might not even live in the woods. More and more often you see "rednecks" living in towns. He prefers the term "country" instead for the mild mannered nice people who tend to live out in the woods, often in competition for resources with the rednecks
.
Of course he also defines two other categories: "herndons" and "rasiophuses", which are two completely madeup words which only he seems to truly know the definitions of. The "herndons" are the slightly less bright people who are uncultured but generally mean well. The "rasiophuses", I don't have a good definition, but it's generally used negatively. Basically rednecks when "redneck" isn't a strong enough term. You have to know him . . . .
Basically, to reference TV shows, The Waltons were country. The Beverly Hillbillies were "herndons". The nastier characters off Dukes of Hazard were rednecks. The characters off of The Hills Have Eyes were "rasiophuses".