"Na" and "W" , when to use?

Need a little help in understanding where to use "w" and "na" when explaining where someone works ,lives etc.

What is the difference between these two sentences that makes one use "W" and the other one "Na"?

Czy jeszcze pracujesz w biurze? This is "w".

Czy pani jeszcze studiuje na uniwersytecie? This is with "Na"

So ,explain to me please the difference between the two? Has it something to do with the size of the location?

It has nothing to do with the size of the location. It's like that simply because of the way it should be used it like when you say.... it has to do with gramar and style of speach.

Czy jeszcze pracujesz w biurze? - Do you still work in the office?

Czy pani jeszcze studiuje na uniwersytecie? - Do you still study at the university?

also literaly W means "in, inside" when NA means "on"

Ahh, of coarse, now it makes perfect sence, dziękuję bardzo :)

It is also ja ide na poczte-to the post office, and ja ide na dworzec centralny-I am going to the main line station. Some nouns take 'na' and others take 'do' but after twenty two years I am not too sure of all the rules.

Nope you're wrong.

Ja idę na stację.

To make it more complicated some cases it's common to use two forms:
isc do stołówki (canteen) or na stołówkę;
do świetlicy or na świetlicę (dayroom).
I don' think both forms are correct but both are common.

no bamse there is only one proper form, what you are talking about is prolly an effect of talking with some minorities who speak very poorly polish or ppl that lets say arent to the highest of standards.

its like that with every country, there are groups of ppl who dont speak the proper language making the most obvious gramar and spelling mistakes and just because they use it right that doesnt make it right.

The correct noun is "do" but approx. 50% polish people is using "na". So it's not about obvious mistakes in this case. If native speakers are not sure which form is proper someone who is coming to Poland and trying to learn language can get really puzzled...
Of course there are poor speakers in every language but sometimes incorrect form is as popular as correct . And it doesn't make it right but can give some problems to find out which form should be used.
I cite what I found on website of Poradnia Jezykowa Wydzialu Polonistyki UJ:
Można przyjąć, że wariant "idę na stołówkę (na świetlicę)" jest dopuszczalny w języku potocznym, natomiast w starannej polszczyźnie należy mówić "idę do stołówki, do świetlicy". Takie rozwiązanie zaleca "Nowy słownik poprawnej polszczyzny PWN", który traktujemy jako źródło wiedzy o współczesnej normie poprawnościowej języka polskiego. - prof. dr hab. Mirosław Skarżyński

That's true. In the U.S. at least, that group is known as "the vast majority" I believe. :)

But it's always best to learn something right the first time, rather than trying to break a bad habit. Thanks for the explanation about w and na - I had some confusion myself recently. :)

Me? When did I write that?

In fact in true Slavic linguistic language 'do' meant as far as something and 'ku' taken from the Russian word 'k' indicated direction towards something. This use of 'do' all the time seems to me to be very lazy and I hate it.

No rule for this. Memorize :-)

Nope. Wrong again. You should really put away that soviet linguistic gibberish that you're soaking in.

The preposition is very ancient and predates any mutual exchanges which took place after the languages differentiated sufficiently to be considered distinct.

The word "ku" appears in Wendish/Sorbian dialects, as well as in Illirian languages such as Albanian. Did Illirian peoples wait a few centuries for the Russian to cristalize and then to incorporate the word into their languages?

In Russian "ku" looses the vowel (in some cases) and it is a simplification of the PreRussian "ku".

Just thought you might wanna know.