When to use "живот" or "желудок" – words for "stomach"

Question

In French, "ventre" and "estomac" can both translate as "stomach", albeit with certain nuances:

• "ventre": a more general, all-encompassing term referring to your (exterior) abdomen which contains your stomach, bowels etc, and a rather casual word.

• "estomac": a part-specific term referring to your stomach as an organ, and a bit on the formal side, often heard on a medical context.

I assume that in this respect, "живот" corresponds to "ventre" and "желудок" corresponds to "estomac".

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But here's the contradiction I've realised. When I say the following in conversation in a casual, non-medical context, I use "желудок":

1) На полный желудок и думается яснее.

... whereas in French only "ventre" fits this context:

1) Il n’y a rien de tel que d’avoir le ventre plein pour se tranquilliser l’esprit.

"Avoir le ventre plein" is something you'd say after having a hearty meal, while "avoir l'estomac plein" is more like what you'll see in a health-related or medical article. So, at least theoretically, I should be using "живот" here instead.

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On a similar note, another contradictory case I notice:

2) И у меня живот вот-вот заурчит.

I use "живот" here, while in French "estomac" more fits this context:

2) Mon estomac ne va pas tarder à crier famine non plus.

... although at least if its French equivalent is anything to go by, I should be using "желудок" in this case.

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So on the surface, "живот" corresponds to "ventre" and "желудок" corresponds to "estomac". But in practice, when it comes to using them in a sentence, as part of an expression, I notice it can work the other way around. So the distinction between "живот" and "желудок" in Russian doesn't seem as clear-cut as I'd expected it to be.

Answer 1

They are "clear-cut".

Живот:

Желудок:

As for their usage in idiomatic (or semi-idiomatic) constructions, it's rarely any clear logic behind.
So as shabunc♦'s answer suggests: you just "remember it".

_{(Although speaking of similar French idioms I guess many will actually wonder why it's "ventre" which is "full". Many idioms sound strange from another language perspective.)}

Answer 2

One can just remember that:

1. болит живот and в животе урчит, живот сводит [от голода, судорогой etc.], are idiomatic and interchangeable with (less used) болит желудок, урчит в желудке, желудок сводит.
2. на полный желудок is an idiom and way more frequently used than на полный живот.

That's pretty much it.

Answer 3

When describing pain, I’d use живот for areas around navel and lower where the intestines are, for example, during diarrhea. And I’d use желудок for area around solar plexus, for example, due to gastritis.