I use the Jet-Puffed Marshmallow Creme to make Rice Krispy treats. I used to buy actual marshmallows, but I wouldn't get around to making the treats, and the marshmallows would go stale (blegh). No such problem with the Marshmallow Creme, as it is in a jar and more shelf stable than marshmallows, I feel.
I haven't noticed any difference between using the Creme and marshmallows for the rice treats, although, the same evening I made the treats, the treats didn't hold together so well when I cut a square out of the pan to try them. The treats fell apart when I picked them up. The next day, the treats had "set", and held together perfectly. So, the Marshmallow Creme treats were better the next day, and tasted awesome, like I remember Mom making when I was a kid. Also, the Creme melts more easily than marshmallows do in the pan on the stove when melting & mixing with the butter.
I like that amazon carries the 7 ounce size jar that I need for making Rice Krispy treats.... my local grocery only carries the larger jar, and I have to eyeball it to try and use half the large jar for the treats. 7oz jar is handy!