Nev - I don't think they are the same. They did have a fairly small handle and were common in sets (especially Marples) of carbon steel tools 30 - 50 years ago. I never did find out what they were for, but that was usual with sets - there were always tools that you either didn't recognise or recognised and never used. It's only in recent decades that any manufacturer actually consulted turners to find out what they actually used.
Same here, there was one in my Dad's old set of turning tools (he died in 1983) and I've never found a practical purpose for it. It's now in my pile of chisels that will one day get ground into some sort of scraper for something specific.
Is it http://picclick.co.uk/Ray-Jones-Woodtur ... 72046.html Ray is a well known Liverpool pro woodturner. I remember buying something similar from him a few years ago. I use for all kinds of things including scraping, skew chisel and as a point tool for difficult places and small jobs.
It's looks like a vee shaped scraper. Used to get them in most of the old carbon steel turning sets. The photo shows the underside of the tool as shown by the tang where it enters the handle.
Photo No.3 doesn't, it shows the working end flat side up - it's ground with two flat facets to a sharp point on the underside. (At least, I can't imagine the thing was designed to be used the other way up.)
Looks to me like a diamond point. I gather they can be quite versatile though I've only ever used one as a skew making a planing cut on small work.
ps. Just looked it up in Dunbar's 'Woodturning for Cabinetmakers'. It's on page 24.