Thanks to fellow CZT Meredity Yuhas for using dictionary definitions to show the difference between doodling and zentangle. 

Doodling VS Zentangle

Doodling (from dictionary definitions):
1. Mindless
2. Aimless
3. Unfocused
4. Used as a distraction
5. Done while doing something else
6. Getting lost in a daydream
7. Unstructured/chaotic
8. Foolish activity

Zentangle:
1. Mindful
2. Done with intent
3. Focused
4. Purposeful
5. Sole activity
6. Attention in the moment
7. Structured process
8. Helpful activity