The new ComparePlus plugin can start comparison from the command line. The command to do so is: notepad++ -pluginMessage=compare new_file.txt old_file.txt
Compare the two files, select View | Diff Context | 0 Lines and you will see only the lines that are different. Click in the side you want to copy, select all ...
After opening both files, from the app's menu bar, select Plugins > Compare > Compare. 'Compare' highlighted in Notepad++. The Compare plugin ...