For me the best way to tell them apart is by the older leaves. The American holly leaves tend to have a dark appearance and a more matte finish. The new leaves will always have a glossy look similar to the English Hollies. I have to be honest, even with this little trick, I have missed the mark a few times. The nice thing about these two types of hollies is that they can be used interchangeably. So unless you are trying to match a replacement shrub you can use which ever one is available.
