subjunctive/optative conjunctions...what is the difference?

[designatus insanorum]

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.

[Koehnsen]

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.