personal description
if they are the same there is no proplem if i ask someone cómo es? or cómo eres?
3 Answers
As I said on your last question, they are not the same, really. One is more formal than the other, so you need to decide whether the person you are talking to should be addressed as tú or usted, and then use the corresponding verb form. There could be 'a problem', as you say, if you chose the wrong one. It varies by region, but a safe bet is tú is appropriate for friends, family members, little children, etc., and usted for people you don't know, older people, etc.
No matter were you are in the world, if you have to ask someone how they are (what they are like), you obviously don´t know them. In this case, you should always use Usted.
The one exception would be little kids. You should use Tú with them, even if they are strangers and they will use Usted with you, assuming you´re an adult.
Example: ¿Cómo es tu hermano? = What is your brother like? and the reply might be: Es alto, tiene el pelo negro es guapo y muy agradable. He is tall, has dark hair, he is handsome and is very friendly.
