How do you mark up changes for a developer?


I’ve designed an mobile app and have to give design feedback to the developer, just on general things like type sizing, spacing etc the usual kind of thing.

My question is; What the best way to compile the various device screens to compare against the original design?

At the moment i’m putting the designs and screenshots side by side in Photoshop and annoting any changes that I want, but this is quite a slow process.

Happy to hear any suggestions you might have or if any one else has the same issues.