Youtube video series by Made by Layers (Thomas Sanladerer) https://www.youtube.com/watch?v=nb-Bzf4nQdE&list=PLDJMid0lOOYnkcFhz6rfQ6Uj8x7meNJJx&index=1
subtractive = cutting away what you don’t want, e.g. aser cutting, wood cutting, CNC milling additive = adding layers and material to create something, e.g. 3D printing