作为 (zuò wéi) as a noun means 'conduct, deed, action' with a moral or evaluative tone — it's about how someone behaves or what they achieve. It overlaps with 行为 (xíng wéi 'behavior, conduct'), but 行为 is more neutral and objective, while 作为 often implies a judgment (good or bad). 事迹 (shì jì) is narrower, referring specifically to admirable achievements.