I'm under the impression that a Diary tends to be something that people keep about their daily life while a Journal can serve the same purpose but can also be used for anything were events are recorded - like a log you keep of your work activities.
Additionally, Diary brings to mind images of something women (young girls in particular) keep, vs Journal which lacks such connotations.
I assume that on most English sites that have a function like Mixi's 日記, that function would be called a Journal rather than a Diary (or a blog, but let's just assume that it had to be either called journal or diary).
Do you agree with the above? What would the Mixi 日記 be called in English, diary or journal, and why?
Both diary and nikki have a root that means day: "dia" is the Latin root for "day," 日 is the Chinese root in Japanese for "day," so I think it's interesting how diary matches the translation linguistically.
Only in American pragmatics does a 'diary' seems dainty or feminine, in reality the word itself does not imply anything feminine. "Journal" is a very broad word that includes a diary entry, but doesn't have to be daily, or about personal life, etc. So, perhaps the translation depends on who is being spoken to or the context it's in... But linguistically, "diary" matches best.