There is a difference in the way the movie and short story handled the shirt scene.
In the movie, Ennis smells the shirts, and to me this was a touching visual, knowing how strong a memory trigger the sense of smell can be.
However, in the short story, Ennis smells the shirts but there is no real scent left:
"He pressed his face into the fabric and breathed in slowly through his mouth and nose, hoping for the faintest smoke and mountain sage and salty sweet stink of Jack but there was no real scent, only the memory of it, the imagined power of Brokeback Mountain of which nothing was left but what he held in his hands."
The short story version seems so much sadder, such a sense of loss and emptiness. Ennis being denied one last smell of Jack seems to simply add to the tragedy of the story.