Explanation

Quick Answer
  • soy= I am/I'm when talking about permanent or lasting attributes
  • estoy= I am/I'm when talking about temporary states or locations

Estoy is also used as an auxiliary verb in the present continuous.

examples
Soy alta, soy mexicana y soy ingeniera.
I'm tall, I'm Mexican, and I'm an engineer.
Estoy cansado y hambriento.
I'm tired and hungry.
Estoy en el banco.
I'm at the bank.
Estoy corriendo en el parque.
I'm running in the park.

Learn more about the differences between ser and estar here!