What is the difference between "all butter" vs "butter"?

Solution 1:

If one wants to be really, really pedantic, one can argue that the sentence

Japan had a lower consumption of all butter, compared with Russia.

is ambiguous. It can be taken to mean

(1) Japan had a lower consumption of all butter in aggregate, compared with Russia (i.e. the total quantity of all kinds of butter, taken together, that was consumed in Japan was lower than the total quantity of all kinds of butter, taken together, that was consumed in Russia).

However, the sentence could also be interpreted as:

(2) Japan had a lower consumption of all kinds of butter, considered separately, compared with Russia (i.e. less X-type butter was consumed in Japan than in Russia, less Y-type butter was consumed in Japan than in Russia, less Z-type butter was consumed in Japan than in Russia, etc. for all kinds of butter).

The other sentence

Japan had a lower consumption of butter than Russia.

is unambiguous: it can only be interpreted as (1).

If one is not really, really pedantic, the possibility of interpreting the first sentence as (2) won't occur to one, unless there is something in the context that calls for interpreting it that way. One will thus assume that that sentence means (1) and will treat the two sentences that the question is about as interchangeable.