How does an external work?

I learned that even if a hack is internal/external you have the same chances of getting VAC banned so how does an external hack work?

internal gets injected into csgo (hook)
external reads/writes memory of csgo thanks to winapi (memory manager)
internal external is external that is injected into other process than csgo -- most safe way

internals are imo easier to do stuff in (assuming you know how to code) but there is risk of getting untrusted if you fail your hook
externals seem more rewarding for me, you can't do some things tho (real soundesp, paintraverse, materialcreation, raytracing) <-- there are limitations in externals/its not worth it making this in external