after 我叫~ only, always add "your name" after 我是~ can add "name" or "call" or "your country" or " your city" 任何可以形容你自已的方式，都能加在我是后面。

是 = the verb "to be" 叫 = the verb "to call"

Thank you everyone. I understand better now.

我是: I am... 我叫: MY name is ..... is it clear to you ?

When you want to tell someone your name for the first time, the "wo jiao" is more normally used, which makes the sentence focus on your name. When you use "wo shi", the intention is usually getting someone who has known your name to distinguish you from others.