From what I've read/seen,
Spiranthes praecox has a white labellum with thin green lines extending outwards, kind of like a firework, and its flowers are sort of more tubular/linear;
Spiranthes odorata has a faint to strong yellow-green wash on its lip – if that helps. The
Spiranthes cernua complex (which does not include the above species) has recently gone under some major revision, making identification even more difficult than it already is, and a lot of the cryptic species have enormous variation/overlaps in morphology and can really only be reliably identified through DNA sequencing. Still, I'm sure it's fun to find and (try to) identify them!
Here's a link to the recently published (long/convoluted) paper:
paper.
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