Macros are the most basic type of automatisaton. Just start to record a macro, do your actions and save your macro as soon as you have finished your actions. Once you have stored the macro you can redo your actions again and again with just one click that executes the macro. You can also edit macros with a text editor to create variations of your actions, to correct bad actions or to add actions and so on. Usefull for small continuos and repeating tasks. You just create your routine very quickly without the need of too much programming skills.
Scripts are a powerfull method of automatisation. Modo supports Perl, Python and Lua scripts. Scripts can store and read user values, make decisions with if-conditions and scripts can do complex calculations. With Python you can import for example the math extension and have access to functions such as cos(), sin(), pi(), log() and whatever else you need. If simple scripts aren't enough you can use the SDK (Software Development Kit) and create real extensions with C+ that can add new item types, channels and funktionality to modo.
Imagine you have a folder full of scripts and you want to create a UI for them, you can do this with the form editor. But you can go the extra mile and do even better stuff: You create a Kit. Kits have their own config. The config describes the UI elements, needed layouts, user values and so on. You just drop them in the user script folder and modo will read the config and set everything up accordingly. Very usefull if you want to share your scripts or use it over different modo versions. Also if you need to reset your main config your Kits will stay intact. Neat!