I'm not sure if everyone knew about this feature, but here it goes.
Most of times, before deploying a new version of your application, you want to review the changes introduced to the modules (eSpaces and extensions) of the application .
If you are using LifeTime (available from OutSystems Platform 7 upwards), this is easily accomplished:
In the 'Applications' section, go to the application you want to deploy and click to see its details.

Once inside the application details, you can see every module that is part of the application, as well as the version that each module is in.
In the image above you can see that developers have changed the 'Customers' and 'CustomersSampleData' eSpaces, because they both have the '+' symbol on their left.
You can also see that there is a 'difference' icon between the two versions of the 'Customers' eSpace.
Once you click it, Service Studio automatically opens with the merge window for you to analyse the difference between these two versions.

I hope this helps you becoming more productive.

You can also compare app versions located in version control or located on the file system: