Yes, they mean a firestik K4 or K4A. One accepts a lug style ring connector and the other accepts a PL-259 style threaded collar. Both have the same antenna atachment method, it just differs in the type of coax you run to it. Make sure they are compatable.
FYI, an SO-239 is the plug that a PL-259 screws onto. Your radio, for instance, has an SO-239 plug, and your coax will have at least one PL-259 to screw onto it.
Let me second what Jerry said about install - make certain to insulate the upper shaft by properly using the nylon washer. If you don't it will not work right, if at all. If you use a lug style mount, both sides get insulated.
“Coming of age in a fascist police state will not be a barrel of fun for anybody, much less for people like me, who are not inclined to suffer Nazis gladly and feel only contempt for the cowardly flag-suckers who would gladly give up their outdated freedom to live for the mess of pottage they have been conned into believing will be freedom from fear.”