(Teachings from Gita)Karma(कर्म) means work/duty and yoga (योग) means discipline. Hence karmayoga means "discipline of action". One who follows the path of karmayoga is called a karmayogi. Such a person performs his duties selflessly; without any desire for rewards.
Ascetism (sanyaas or सन्यास) and karmayoga, both are ways to reach God but one who follows the latter is above an ascetic as he who's adopted karmayoga has already embraced ascetism by not harboring feelings of love or hate and by not having any expectations. He goes a step further by performing his duties but renouncing the right or privilege of being the performer; by not desiring any fruits for his labor. To become an ascetic one has to cross the path of karmayoga.