If you check various dictionaries, as I'm sure you have, you always see 'revenge' and 'retaliation' listed as synonyms, and they are -- along with other words like 'retribution', 'reprisal', 'payback', etc. While each may be described in terms of how it is "traditionally" used, that doesn't mean that there isn't a lot of overlap. To really understand the differences, you will have to study them in context. As I perceive the difference you ask about here, 'revenge' connotes a more visceral, emotional reaction, perhaps on a more personal level. 'Retaliation', on the other hand, seems to apply more to larger scale political/corporate or military situations, and may elevate the actions to a higher level of legitimacy. However, that doesn't mean you won't see one country (the "good guys") describe the actions of another country (the "bad guys") as 'revenge', or 'acts of vengeance'. Regarding "in ..." vs. "as retaliation for", they are interchangeable in many contexts, but not all. It depends on the verb preceding the phrase, Examples: ... The rebel attack was launched IN retaliation for government crackdowns. ... The rebel attack was launched AS retaliation for government crackdowns. Now compare these: ... The rebel attack was IN retaliation for ... crackdowns. [not AS] ... The rebel attack was described AS retaliation for ... crackdowns. [not IN] In #s 1 and 2 above, either phrase can be found in published works. In #3, forms of the verb "to be" seem to call for 'IN' as the more natural choice -- "it was in ...", "they were in ...", "it will be in ...", "they have been in ...", etc. In #4, there is a clear difference in the verb "described" which is only referring to the attacks and must be followed by "AS". Similar examples would be "considered as ...", "proposed as ...", etc. -- and your example above, "pushing ... as ..." { ... I've reached the word limit -- see additional comments below }

They actually are similar. MLK is saying them together in that sentence on purpose; that revenge, aggression, and retaliation as solutions to problems should be rejected in favor of using love instead. Jakir's comment about revenge being about "getting your own back" is also true; "revenge" seems to carry with it a personal vendetta against the person while "retaliation" may not have that connotation. But the difference is slight, and not exclusive. If I were you I would treat them as mostly the same meaning. (Also, LOVE that you're using MLK! He's got some wonderful quotes =) )

To me, "retaliation" is a kind of "hitting back", usually with the same amount of force. An eye-for-an-eye idea. "Revenge" has a sense of punishment about it, and suggests some planning and hatred are behind the action. It can be the same level of payback, or even greater (to discourage any thoughts of retaliation by the other party). Revenge is a dish best served cold. Revenge digs two graves.

Retaliation - action taken in return for an injury or offense. Revenge is getting your own back on someone for something thats happened so basically payback. I guess both words have pretty similar meanings. :)