Reflective thread  is a specially developed thread with an extraordinary high level of retro-reflectance coupled with good sewability.
Coats Signal thread is primarily for high visibility fashion applications. It is not for safety wear where strict norms for reflectivity values are specified.

Decorative use as top cover thread in flatseam ISO 602 / 605 / 607
Needle or bobbin thread in decorative, non-construction lockstitch seams