Welcome to the mysteries of Polish nouns. "Wode" is not actually a word (at least not in this context). Perhaps you meant to enquire about the difference between "woda" and "wodę"?
So, "wodę" is indeed used when it is the direct object of a verb, such as when "drinking" is involved; the so-called Accusative case.
However, some verbs force the noun into other cases, such as "potrzebować"("to need") which needs "wody" and "być"("to be") which needs "wodą".
See https://en.wiktionary.org/wiki/woda#Polish and 'show' the declension for more details!
Oh, and when "water" is the subject of a verb, you'd use the dictionary form, which is "woda".
Russian, Polish, and other Slavic languages are related to some degree, and consequently have some similar words. (Он. Она. Хлеб.. Яблоко.) . Czech, for example: On. Ona. Chléb. Jablko.
On a recent trip to Slovakia, I found that my fluent broken Polish worked wonders :-)