How do I display 2 photos side by side on photos

Hi,

This might appal the gurus, but it works:

1. Drag the photos to the desktop.

2. Open separately in Preview.

3. Resize/arrange as desired.

4. Using 'Grab', take a screen shot of the result and name/save to desktop.

5. Drag into Photos album as required.

There is no way to view two photos side by side in Photos. If you're in full screen mode you can have the tool bar available by selecting this menu option when viewing a photo full size:

Tell Apple what missing features you'd like restored in Photos via https://www.apple.com/feedback/photos.html.

The only ways to do that in Photos.app currently are clumsy workarounds like creating a unique keyword & assigning just to the two photos you want to see side by side, then searching on that keyword or creating a smart album with that keyword as its only criterion. You can toggle between the edited & unedited version of an edited photo in the edit window by holding down the M key, but even in edit mode you can't see both versions side-by-side.

Please be sure to use the feedback form to tell Apple about each of the missing features you want to see in the app. The more users do this, the more likely it is that Apple will make adding them a priority.

why does Apple omit features ?

Only Apple can say for sure but typically it is because the more features there are, the harder it is to debug them all, & the more difficult it is to integrate them with system services. Remember, iPhoto was not all that feature-rich when it was first released -- it is in its ninth major release.