Standard-duty (like S6 & 318), HD (like RR/GTX), XHD (like Hemi), and SS.
That's what I recall from sales literature, haven't checked difference between standard (4.5 leaves, IIRC) and HD.
Published spring rates seem to be all over the map depending on the source. The difference I've noticed over the years is that the lighter-duty springs seem to sag more than the heavier-duty.
Only difference is she is saying HD is hemi, XHD had 6 leaves, both sides. Hadn't heard of this.
I'll probably just go with the usual hemi.
