けれども = though/in spite of/but/however/although Here is a page of synonyms of けれども in Japanese. https://thesaurus.weblio.jp/content/%E3%81%91%E3%82%8C%E3%81%A9%E3%82%82 I think that けれども shows canceling things that should/would happen or might have happened. Examples: 金持ちだけれども幸福ではない. He is rich but not happy. 試合は当初、明日に予定されていたけれども、雨のため中止となった。The game was originally scheduled tomorrow, but it was called off due to rain. 確かにそうかもしれないけれども it's true, but... ただし = however/but/except/only/in this regard, however/provided Here is a page of synonyms of ただし in Japanese. https://thesaurus.weblio.jp/content/%E3%81%9F%E3%81%A0%E3%81%97 Examples: ただし～ならば Provided that... ただし、この件には異論がある。In this regard, however, here is another view. ただし、このケースは除く except in the case ただし、一定の条件下で but only under certain conditions