"agony" means extreme and generally prolonged pain, but can be used lightly as an adjective. Agony is usually a state of mind. "affliction"-This one is usually related to actual sickness. It can also be used metaphorically when a circumstance is so bad that it can be likened to a sickness).

The two words basically mean the same thing. They are synonymous with each other. Both are nouns describing a state of physical or mental pain and suffering. Hope this helps! :)

Affliction is a suffering caused in general for some moral or phisical suffering. Agony is a word that comes from greek , meaning "fight". It refers to the last fights the human being must face just before its own death. One person is "in agony", when he is close to die. (you can put both words in the www.linguee.com and you will have many sentences related to them) Please excuse my mistakes in english.