Practically any of the exploding shell used at the time. I presume the mixture inside consisted of sulphur, charcoal, and potassium nitrate.
Canister was short range only
Most of the long range guns, by the mid 1860's, were firing cylindrical shells from rifled bores. Most of these were of the exploding type. A 10 pound Parrot had a range of over 2000 yards firing an exploding shell from a rifled bore. That is a range of well over a mile.
The navy used solid shot and explosive shells in the Civil War. So did the army. These can't be confused with Greek Fire at all
No confusion is necessary. Greek fire is a figurative term that most likely refers to exploding shot in general. For you to take its use literally is particularly absurd considering that the historical Greek fire was only useful for dumping onto enemy ships etc. at close range from the walls of Constantinople etc. By 1860, Greek fire in the literal sense, even if its formula had by some miracle survived, would have been comparatively ineffective and useless as a weapon in comparison to gunpowder. Put differently, you are exhibiting an anal retentive characteristic of Wlatian proportions.
I know you feel that you can freely speak for people long since dead, but it's just as likely that the term was meant to whip up support for the southern cause among those who had no idea of what was really going on.