>As a native speaker of Slavic language, I've never understood the need for differentiating between "THE table" and "A table". It's useless and clear from the context what is meant (note that both are different from "THIS/THAT table", which I do NOT deem useless.)
One differentiating example could be:
One person says to another:
1) Put it on the table.
vs. saying:
2) Put it on a table.
(Where, in both cases, by "it", they mean some object, say a book or any other thing).
1) would imply there is only one table in the room, so "the" was used.
2) would imply there is more than one table in the room, so "a" was used, meaning put it on any table you wish, it doesn't matter which one.
One differentiating example could be:
One person says to another:
1) Put it on the table.
vs. saying:
2) Put it on a table.
(Where, in both cases, by "it", they mean some object, say a book or any other thing).
1) would imply there is only one table in the room, so "the" was used.
2) would imply there is more than one table in the room, so "a" was used, meaning put it on any table you wish, it doesn't matter which one.