全力 (quán lì) means “full strength” or “with all one’s effort”—it emphasizes putting all available energy into an action. Compare with 大力 (dà lì), which means “vigorously” and often describes strong support or promotion (e.g., 大力支持), while 充分 (chōng fèn) means “sufficient, ample” and focuses on having enough resources, not the intensity of effort. The HSK 6+ synonyms 奋力 and 竭力 are more literary and extreme, meaning “strive with all one’s might.”