Notion:
- General idea or belief
- Vaguely defined impression of a fleeting idea and more subjective
- Sparks of ideas
Thought:
- Mental process of reasoning
- Involves a conscious or unconscious process
- Involves ideas, images, feelings
- Mental processes that fuel notions
Concept:
- General idea or understanding
- Defined and objective
- Involves past experience or knowledge
- Fully formed, well-defined ideas resulting from thoughts
