As popular in France as anywhere, saucisse is sold (usually, but not always) raw, ready to barbecue (la grillade) while saucisson is smoked or dried and ready to eat. The intestinal casing is called the boyau.
chair à saucisse: sausage meat
lukinka: small garlicky Basque sausages
saucisse au couteau: a pork sausage made of lean pieces of pork cut with a knife and pork fat, and seasoned, then stuffed into an intestine. From the Vosges.
saucisse cru (à cuire): raw sausage that must be cooked
Images by Reflets de France, Salimfadhley on Wikimedia Commons