They don´t mean the same thing. "Ser" is used for permanent or lasting attributes, and "estar" for temporary states or locations.

Ser for fixed characteristics: El coche es rojo, Tú eres alto, Ella es irlandesa. Estar for temporary characteristics: El plátano está verde (no siempre es verde, puede estar amarillo), John está feliz (but not always, another days may be sad)

easy to understand Soy= Is sometimes used with YO (subject) or with out. and is used to describe personal atributes like origin,. Yo soy de México,Personal atributes, soy blanco, soy negro. Estoy= Is sometimes used with YO (subject) or with out. and is used to describe a ubication, Yo Estoy en la tienda, or personal situatión.Yo estoy enfermo, yo estoy ocupado, yo estoy enojado, yo estoy escribiendo.

ESTOY = I am at my university. SOY = I'm from Perú So, You use "estoy" when You want say that you are in a place or say how are you feel. And you use "Soy" When You want describe yourself (height, nacionality, skin color) I hope I help you with my answer and sorry if my grammatical is wrong :/

Grammar book time!