I’ve always looked at it this way when talking whole states only and not pockets in different states:
Deep South - these states are as southern as it gets with the exception of maybe one metro area - Mississippi, Alabama, Georgia, South Carolina
South - overall very southern, but maybe there’s a pretty substantial subculture there - Tennessee, North Carolina, Louisiana, Arkansas
Southern adjacent - fair amount of southern qualities, but can’t be wholly classified as southern - Texas, Florida, Virginia, Kentucky