How to tell?

[alwinearcher]

One great thing about hunting bears over bait is you will have the barrel to compare the bears size to.
Really helps in field judging!

[huntnnw]

mature boars.. become pigeon toed and have a sway with their walk.. dead give away.. a sow will have the appearance of a large ass and narrow front end

[MAVsled]

I go by looking at the bear's head.
Large,squarish head, ears more on the side and the angle of the forehead2snout from a side view. Agree that younger bears are harder to identify as boars. pretty hard to look between a bear's hind legs, even with a rear view. too much fur 

My labrador dogs help.
How?!
look at the head of an adult male lab and an adult female lab; straight on, sideview and slope of forehead to nose.
My male lab's head is much more blockier appearing and wide with blunt snout. The female lab's head appears very different. I see this trait in other people's labs too.

both my choc labs were of the same age and from same litter. But I lost the female to a freak accident a few years ago 

[high country]

The wdfw offers a great video to eastside spring hunters, it is a good watch. Long story short, a big ass and short neck is a dead giveaway of a sow. It is easy to tell a boar from a sow, it is tougher to tell a good boar from an average one. Just take the time to watch....it becomes obvious. It helps to get out and see a lot of bears, the right area in id, you may see several a day.