Do you have any idea of dates photos were taken? One on the right looks a bit older - hair receding.
There is no date on the back of the right photo but if it is Edwin it could be around 1916 (he would be 25), if not i think it could be 1912/1913. The one on the left i got from an ancestry tree, they said it's dated 1915 meaning he would be 24 which looks correct. The photos are only (supposedly!) a year apart so not to much would have changed.
No name are on the back of the photo so i have been going off looks which has been proven quite difficult.