I think that mostly, "diary" indicates "日記" or "日記帳" in Japan. "日記" = a book in which one keeps a daily record of events and experiences. There is a word "日誌" in Japan, "日誌" is business-related, not for private use. As for ”journal", I think that most Japanese don't use the word "ジャーナル"(journal). "ジャーナル" is a 和製英語(Japanese-made English), 　 "ジャーナル" = a newspaper or magazine that deals with a particular subject or professional activity, or a daily newspaper in Japan. I think that most Japanese say "雑誌", "新聞", or "定期刊行物" instead of "ジャーナル".

if you mean by the word diary a record of personal events which is to be read basically by yourself, it is called 日記 in Japanese. And if you mean by the word journal a record of particular events which is supposed to be read by other persons, it is called 日誌, like 航海日誌 a voyage journal(?). If you call it 航海日記, it is a writing for yourself, a personal one; and if 航海日誌, it is for everybody, a kind of a report, or a public one. And if you mean by the word journal a periodical or a magazine, it is sometimes called as ジャーナル, like 鉄道ジャーナル http://www.rjnet.jp/. The Japanese word ジャーナル has practically no meaning. They call it ジャーナル because they think it sounds good. In other words, you can't call it 鉄道日記 or 鉄道日誌 because 鉄道ジャーナル is a proper noun. Or sometimes it is called 季報, a quarterly journal. http://www.iae.or.jp/reviews/iae_reviews/ And if jokingly translating "The wall street journal", it will be "壁街日報" The word 記 stands for "a writing" like 記述、記載、記事、記述、記録、記帳、筆記、記録、戦記、書記. They are personal or public. The word 誌 also stands for "a writing" and rather a "public writing" like 日誌、雑誌、戦誌、誌面. In other words, even a mad man can write 日記 which is even interesting, but they are not capable of writing 日誌, which would end up with a useless thing.