What is the difference between пока and ещё?

Question

the difference in these two words is something I don't understand, is it just me or do those words actually mean the same thing?

for example: if I want to say

I don't Know yet!

do I say

пока не знаю

or

ещё не знаю

??

Answer 1

In the context you are using it, the words indeed have a similar meaning - "yet". Fun fact, you can also say:

Пока еще не знаю.

Пока in the meaning of yet is actually the short of пока еще. From Ushakov's dictionary:

ПОКА́ нареч.

... со словом “еще” или без него. До сего времени, до этих пор, всё еще. Сведений пока нет. Пока еще ждем. Пока еще не уехали.

Answer 2

They're really similar (and can be used together as the previous poster suggested), but intuitively, I'd say Я ещё не знаю implies a greater degree of confidence, imminence, and/or proximity in time, compared to Я пока не знаю, of your knowing eventually. You could say that пока is neutral expectation-wise, while ещё is somewhat on the optimistic side.

Come to think of it, the latter is a better way to describe it, because with undesirable eventualities, the confidence factor is reversed: Я ещё не умер is definitely upbeat compared to the resigned-ish Я пока не умер.

On third thoughts (sorry but I'm really making these little discoveries as I go along, it's fascinating), the very neutrality of пока can, with these undesirable outcomes, give it a "so far so good" touch that doesn't quite work with ещё. E.g. Съел-таки (=я всё-таки съел) эти просроченные консервы. Пока не умер.

So in the end, what I could definitely say is that ещё is about a more likely, or temporally nearer, outcome — which is consistent with its being more "optimistic" because when it's not about being "almost there", it's about defying the odds.