- He has eaten. (Does it mean he eats something?)
- He is eaten. (Does it mean something ate him???)
Do I distinguish correctly the difference between the meaning of each of those sentences?
I think you are right grammatically.
However, the first sentence means you have finished your food.
You may finish the second sentence as:
He is eaten by a vampire.
haha!
It would be hard to imagine a way that the second sentence could be used in the present tense just as it is, even though it seems “correct”. As you can see, your first sentence is present tense and your second is past tense. “He was eaten” would seem to be a more useful tense for this meaning.
But, similar to what was said above, you could say something like “He is eaten by a vampire every Thursday” but “He” would have to be something that could come alive again and again.
Here is something to hopefully clear this up:
I am going to eat a pizza. (The pizza is still there and I am not yet consuming it)
I am eating a pizza. (The pizza is still there but it is being consumed by me)
I ate the pizza. (The pizza is gone because it has been consumed)
I have eaten a pizza before. (At some undefined time I consumed some abstract pizza).