edition ɪˈdɪʃn̩
eleven ɪˈlevn̩
Edition, I hear this e sounds like a as in (a pen).
Eleven, e sounds like short e.
That is one of the best known characteristics of the English language. A blessing and a curse. That is why you must always have the pronunciation of the word available when you learn English.
For more "amusement", read this discussion about the reading of: cough, tough, bough, through, and though.
Another "amusement": the letter "c" is read differently each time it appears in "The Pacific Ocean".