Hi, to begin with, realize that the Style panel of Webflow relys almost entirely to CSS rules, so you can start to read here:
So, Auto doesn’t exist, it could be called Static. it means the elements is positionned in the flow of other elements… after the precedent, before the following.
Relative positions it relatively to the static position. So in your 3rd image, it’s 20 px upper than Static. Relative is also used as is with no other value. Changes nothing but the element is considered “positionned” and used as a reference for any child element positionned absolutely.
Absolute is positionned regarding the closest positionned parent (read above)
Fixed is positionned regarding the browser or viewport.