Reading through this article…. couple of things here:
1. Index Seek and Index Scans differ. An Index scan goes a complete scan over your index whereas an index seek navigates to the respective node based on the Unique Key pattern algorithm which is part of the index.
2. You can also mention that the storage structure for clustered and non clustered indexes are trees as well as mention the way to navigate to a particular node from the root making it more useful for the readers.
3. The navigation to 156 in the diagram takes place from 101 in a index scan…

Since most of the time I do not code so regularly as I should be doing I keep cheat sheets such as this:-
Table Scan > Index Scan > Index Seek.
But great article none the less.