Are you talking about the pellets used in a pellet stove??
To save a literal dollar, I tried a bag of stove pellets...once. They do look a like, and here equine pellets here are $5 a bag, where the stove pellets are $4 a bag. My experience...the stove pellets didn't even need to get wet before they started to turn into a powder. The smell was different too, not fresh like the equine...not stinky mind you, but different.
After that single bag...went back to equine pellets.