SBS is solid bleached sulfate. It is virgin fiber, smooth, and white. C1S SBS is coated on the print side. C2S SBS is coated on both sides, so the inside of the carton is white too. Cosmetics, health, and anything that gets opened in someone's hand usually want SBS.
CCNB is clay coated news back. The print side is white and clay coated. The back is recycled newsprint, so it looks gray. It prints well and costs less. It is the usual board when the inside of the carton is never seen, such as a dry-food or general retail carton.
Fampack prints both, plus kraft bending chip and TMP. Calipers we quote are 12, 14, 16, 18, 20, 24, and 28 point. The right one depends on what the carton holds, whether the inside shows, and the budget. If you are not sure, send the product or a sample of the carton you have now.