My textbook is Schoder/Horrigan/Edwards; I am teaching myself.
When I reached the chapter introducing the subjunctive, the vocabulary lists several conjunctions with the same meaning–hina, hopos, ophra. My question is, as you may have guessed, is if these words are interchangeable, or if have different shades of meaning. I mean, I fully expect them to not be interchangeable, and what I am really asking is whether anyone knows how these words are different from each other. The textbook, as far as I’ve looked ahead, does not enlighten me on the matter.
According to what I was taught, those conjunctions (except for ὂφρα) all mean “in order that,” with no shade of meaning. In other words they are interchangeable.
I checked Smyth (§ 2193) and it confirms everything above. But ὂφρα is strictly while or until in Epic and Lyric according to Smyth; ἒως for the same in Epic.
There is a full explanation of other conditions, so please consult Smyth § 2193, which I believe is still available free as a pdf download in Textkit.
I am sure some of the experts here like chad or annis can shed further light on this.
Edit: with regard to ὂφρα and minor text edits.