In general, thread refers to a very thin string used for sewing, while yarn is a thicker, sometimes softer, string used for knitting, crocheting, etc.
There are different weight threads, usually made from cotton, with sometimes a shiny viscose added for holiday use. Weights vary from 3 to 30 with 3 being the thickest to 30 being the thinnest. There is also tatting cotton which is the thinnest of all, if you really want to drive yourself nuts and try to crochet with it.
Thread was used a lot in the doilies and filet crochet of yesteryear. Doilies are still made, but the cotton thread is also used in scarves and bookmarks these days. I have made teddies with thread also, same pattern as worsted weight but with thread and a much tinier hook. I have seen patterns for nativities and for chapstick holders also.
difference between spun yarn and filament yarn
Rowan Soft Lux yarn; This yarn consists of fuzzy strands, wrapped in a single ply of gold metallic thread this is used for making jackets, RYC's "Soft Tweed" is a soft, fuzzy yarn used for making blankets and skirts.
A virus runs in a thread, as do all programs. The difference between a generic thread and a virus is that the thread may not be harmful, while the virus generally is.
Yarn is fibre; bobbin is a storage reel for fibre.
A collective noun for thread is a spool of thread.
Gassed yarn is yarn or thread, which has been quickly passed through a flame or series of flames. The purpose of which, is to burn off the fibers projecting out of the yarn/thread, this will make the yarn/thread round and smooth. This is most often done with the better qualities of yarn/thread, such as poplin; venetian; violes; gaberdine; and Egyptian cotton; for example.
The process of producing yarn and thread is referred to as spinning. Fibers are twisted and spun together in this method.
Some times needle point is done with a thick yarn, not sure if embroidery yarn is what it's called but there is embroidery thread which is more commonly used in cross stich and making friend ship bracelets.
Since neither word describes a natural fibre, the difference is probably vocabulary choice.
Textured yarn has for lack of better words a texture like confettie, eyelash, or fiber look to it. Micro yarn is very thin yarn.
In computing terms - A 'thread' is a topic of discussion, and a 'post' is a response to the 'thread'.
soft silk yarn is strong as comparable thread of steel