All ravens are crows.
Not all crows are ravens.
Note size.
Distinguish shape of tail feathers.
Listen for their calls.
Now, apply the above to poetry & prose. Noting that beauty unifies.
Raining harshly this morning; it appears ravens & crows have self-grounded. Exploration of differences on temporary hold. Thus, haiku (the cat) sleeps.
About food. Huge difference between tuna (recognizable as fish) and tuna (contained in can). Both are tuna (I think).