I grow both, and I believe that the first photo is Endless Summer, and the second is Annabelle which has whitish leaf undersides.

Agree that the first looks like my 'Endless Summer'.

tj

The leaves of the first one look like a mac's (ES) leaves. The second pic had a dried out bloom that resembles an Annabelle bloom and the serrated leaves look like Annabelles but they are too small to know for sure. I am going to try with my glasses backwards next -ha!- to see if that helps me. ;0),

Feel free to cut dead wood by May. Maintain 2-4" of organic mulch too.

did you live there when they were in bloom?..if you recall the bloom colors you can determine which is which..Annabelles have white blooms..Endless Summer blooms are not white..could be pink or blue..color varies depending on your soil..

This link may help in the future:

https://plantaddicts.com/types-of-hydrangeas

But I doubt you will need it if it was just a matter of choosing between those two choices. ;o)