I don't have a scale available, but I do own both G19 & G26. There is a definite difference between the two. I have issues with my back and have been carrying the G26 almost exclusively. The G19 is just too much for me to carry for any length of time. The Glock site lists the two with a weight difference of almost 4 oz. (3.88 oz.) It may not seem like much, but it does make a definite difference. Being more compact also makes it seem lighter than that to me.
P.S. I carry a G19 mag for a spare.