What is the difference between "ну" and "значит" in usage? Can they be used interchangeably? I believe they both mean something similar to "so" or "well" in English
In the following explanation, translations are not at all word by word translations, and each translation relies on the context of the discussion used in the answer.
"Значит" translates to "means".
It is used however in some cases as a start of a told explanation, like this:
Значит так: я пойду за детьми а ты жди мастера
which would translate roughly to:
Ok, so I will pick up the kids and you wait for the repair man.
Sometimes, similarly, the same word can be used to ask for a confirmation on the explanation:
Значит я пойду за детьми?
So, I will pick up the kids?
Indeed, the usage of the word "значит" does in some cases coincide with the english "so". But when you try to replace "well" in the same sentences, it won't work. "so" gives a command tone to the sentence, while "well" is kind of unsure.
well, maybe you will go to pick up the kids and I'll wait home?
this does translate to something like this:
ну может ты пойдёшь за детьми и я подожду дома?
If you substitute the word, you'd have to change the tone of the sentence as well.
Another case of "ну" is for answering the same kind of question:
ну ладно, поеду
well OK, I'll do it
or answering a stupid question:
ну используй мозги, придёшь к ответу
well, use your brains, and you'll come to the answer
As you can see, in both languages, the given examples would not support word substitution without slightly changing the meaning.
In its usage as a filler word, значит generally signifies that the speaker is pursuing a particular train of thought, i.e. that they're on track and know what they're going to say next, even if they have a momentary difficulty. Ну, on the other hand, is largely the opposite, an expression of looking for a thread to follow. You can think of значит as reflecting the mental equivalent of consulting one's notes, whereas ну is like flipping through the notebook to find the right page.