Thanks for posting that picture. It looks as if it has a lot of wood chips mixed in it as well. This is pretty common, since the demand for bark exceeds the supply. The problem with softwood chips is that they tend to mold, developing an overgrowth of mycelium that can render the soil waterproof. The result is that it can break down to a waterlogged, airless muck in as little as one season. (These are both much bigger problems in containers)
Bark is the tough, water-resistant layer that the tree develops in order to protect itself from pests and disease. If you look at dead, standing timber, you can see trunks where the core of the tree has decomposed, leaving a shell of bark standing. Because it breaks down much more slowly, it maintains its structure longer and promotes a healthier, more long-lasting planting medium, particularly in pots.
Canada Red and similar products would be fine as a garden mulch, (which is what we're talking about, I guess) and once it had aged you could mix it in, but you don't really want to incorporate a lot of raw or actively rotting wood pulp into your soil.
When I buy plants from Yucca Do and Plant Delights, they arrive in some of the best potting mix I've ever seen. The bark in it is instantly recognizable as such—it's the type of bark (pine or fir?) that looks like jigsaw puzzle pieces. I've never seen it offered around here.
So far, the best bark I've ever found locally is sold as ground orchid bark. I don't see any pulp wood in it at all, and I've had very good results using it in container mixes, but it's too expensive to use as a general garden amendment.
[Edited for clarification.]
