I'm trying to identify an existing hydrangea for someone, and believe I have it narrowed down to one of four varieties.

It looks like a woody shrub, about 8-10' tall currently, has multiple stems. Owner says it blooms white cone shaped flowers. It has kinda oval shaped leaves with point at end, edges are almost smooth, and if you look close enough it appears to have small hairs on it. Branches are opposite each other.

I believe it is either a peegee hydrangea, limelight hydrangea, kyushu hydrangea, or tardiva hydrangea.

Can anyone give me any clues how to distinguish between the four and narrow it down?

thanks