이에요 / 예요 are used in the English sense of "to be" equal. 물이에요 = It is water. 학교예요 = It's a school. 있어요 is used in the English sense of "to be" (exist) and "to have". 물 있어요 = There is water. I have water. 친구 있어요 = I have friends.

Hello Giulie! Your question is indeed very vague, and this is veeeery basic Korean that many many websites provide wonderful information about. You should check these sources out for a good understanding of this basic grammar. http://www.talktomeinkorean.com/lessons/l1l5/ --> for more info about "이에요" http://www.talktomeinkorean.com/lessons/l1l10/ --> for more info about "있어요" IN A NUTSHELL ==================== 이에요 is the polite way to express equivalence. One thing is another, this is used for "Noun is noun" and "Noun is color (noun)" [Thanks for the correction, @Mojave] e. g. "I am a student." // "The apple is red color." 있어요 is the polite way to express existance in general ("there is...") // placement ("over there is") and possession ("I have got...") e. g. "There are many ways to read" // "The car is here" // "Do you have money?"

아, 도대체 어디서 부터 설명을 시작해야 할 지 ....어째서 구어체 때문에 헤메는 외국인들이 이리도 많은 지... 모르겠네요. 그냥 무턱대고 답변할 것 같으면, 1. '있다'와 '이다' 의 의미와 그 구별 2. '이다' 의 구어체, '이어요', '이에요' 또는 '에요' 3. '있다'의 구어체, '있어요' 4. 구어체와 문어체. 이와 같은 내용을 또 다시 쭈욱 설명하려니..... 힘드네요.

Can I look some example sentence? It is too vague.