I'm also interested in learning more. These are pictures from an outfitter in Saskatchewan. These two bears are the same age and the sow is far bigger then the boar. I'm beginning to think accuratly judging bears is a myth.
it's the hardest thing to field judge in NA I believe (excluding sheep and goats which I cannot say either way, but know that's challenging too) I saw a tank of a sow this year, was confident it was a boar, but quickly decided it wasn't one I would shoot, then I spot the little fur balls rolling around wrestling below her..... it's a non stop schooling looking at bear to me, and those things keep me aware that things aren't always what they seem in the bear woods.
the pics the OP posted are pretty straightforward though, it's a boar, it's big enough it leaves no doubt there.... and I believe it's a good one.
spring bear are even tougher to judge because they aren't filled out, and their coats vary so much. my friend killed a nice boar the other night (just shy of 19" green) a respectable boar.... it's body was thin, and it's coat was too, and kind of sparse hear with that weathered reddish hue... not the super fluffy shiny jet black we normally see on a good boar in the spring.
by that bears body shape, it would have been a tough one for me to judge, especially at the distance he shot it (I think 670yds) they are hard to judge because we have nothing to compare them to in their surroundings unless we know the area very well, and know how big the stumps/rocks/trees are where the bear is walking.
BIG bear and little bear are pretty easy to tell, everything in-between is very tough to me.... i'm not much of a trophy hunter, but I am with bear just because that's the only way I know for sure i'm not shooting a wet sow.... big ones are easy to recognize, but if you are wondering if it's big, it's not.... I learned that lesson once, and don't care to again.
I shot a fall bear a few years ago that I knew wasn't little, but didn't know if it was big, ended up being an 11yr old boar, but it was sub 200# and I was pretty bummed out with the small amount of meat I got from that bear.... once I got the hide and fat off, there wasn't much..... kill a big boar (300+lb) and you get a pretty dang good pile of meat! they are just so muscular.
I do think that's one thing I enjoy about spring bear hunting, it's challenging in every aspect, and I get a lot of encounters per filled tag.... get my monies worth out of them.
I lost track now, but I have seen 15-17 bear so far this spring, and of those, only one was a for sure shooter, with another 4-5 maybe bear... the maybe bear never turn into anything because bear in the spring don't hang around long enough to turn a maybe into a yes or no.... they don't quit moving