[jmillikin]

I've never seen 「同志」 used in real life. It seems to be a specialized term comparable to English's "comrade". Wikipedia thinks the Turkish equivalent is "yoldaş".

For the differences between two Japanese words with the same pronunciation and similar meaning, Yahoo Answers is a surprisingly good resource. You can also do web searches like [[ 「同志」と「同士」の違い ]] to find explanation pages. In general homophonic kanji is an area that even native speakers struggle with sometimes, so there's lots of non-English coverage available.

https://detail.chiebukuro.yahoo.co.jp/qa/question_detail/q10...

"「同志」と「同士」の意味の違いについて教えてください。"