What's in a name? Here are some notes that provide some information on these different names for the same knot. Repeat...for emphasis...
The names are labels that distinguish their uses ~ users ~ and techniques of tying them.
The Bookbinders' Knot is a Sheet Bend, but tied with thread instead of rope ~ and tied in a different way.
The Bookbinders' Knot is Weaver's Knot ~ tied with thread of comparable thickness to that of the weaver ~ but in a different way.
The Bookbinder's Knot is a a Becket Hitch ~ where the beket is a loop of thread rather than metal.
I am inventing and defining a suggested name for the useful knot used by bookbinders and bookcrafter's when they need to lengthen their thread in mid-job.
A Bookbinders' Knot is a Sheet Bend tied by collapsing a Simple Slip Knot around another thread of similar thickness. It looks and acts as a Weavers Knot ~ but the loom-minder or weaver ties it in a different way.