HOP STAND V WHIRLPOOL -

There isn't really a difference.
I guess you can do a hop stand with out a whirlpool but most would do the hop stand during a whirlpool.
Time and temperature are totally recipe dependant.
History.
In the old days, before neipas, lol , maybe 5 or 6 years ago, a whirlpool was just that, a whirlpool at the end of boil to centre the trub and make it easier to collect clear wort from the side of the boil kettle, especially when using flameout hops, hops thrown into the kettle after the boil was turned off. So I guess they are whirlpool hops and also a hop stand.
When NEIPAs came along fro some reason people wanted beers that weren't bitter, weird ay?? So they started chilling the wort a bit in the whirlpool before adding the hops so to reduce the bitterness gained from the hops, these temperatures change too, some will do it at 95c some will do it at 80c and everywhere in between.
To me a hop stand originally was like what was called a hop steep, more for extract brewers that would boil a small amount of wort, add some hops, and it just stood on the bench for 5-15mins and then added to the rest of the ingredients.
But it seems since programs like Brewfather came out these terms have been changed and repurposed. Brewfather seems to call hops added to the kettle after flameout, flameout hops, a hop stand and doesn't use the whirlpool term at all. Maybe it was a language thing?? I don't know, but people have taken Brewfather as gospel and these are the terms that are mostly thrown around in online forums etc these days.
Brewfather defaults at 80c for "hop stand" hops, where most breweries will still do it at flameout without chilling or maybe at 90-95c just to knock the the top of the heat off.
Although the 80c "hop stand" was only for NEIPAs it seems home brewers at least, are doing this for all sorts of beers, personally I think it a waste of time and energy in most cases for styles of beers other than NEIPAs and possibly some Hazy IPAs that probably shouldn't be called IPAs because they aren't bitter! It also takes uses more hops because the cooler temps have a little harder time extracting the hoppy goodness out!
There are no set times for whirlpools or hop stands. I guess old days you rarely did one over 20mins, these days with lower temps some do them for 30-40mins, I havent seen many longer than that..
Cheers