These phrases mean basically the same thing. They compare people who continue to sin on purpose to a person who uses all his strength to keep pull a heavy cart along. The word "emptiness" means it is all in vain. God will judge them and they will not benefit from their sin. Alternate translation: "to those who work hard to sin like a person who drags a cart by a rope." (See: [[rc://en/ta/man/translate/figs-doublet]] and [[rc://en/ta/man/translate/figs-metaphor]])