Try, then. :)

"She always smiles."

"She IS always smiling."

Yes, there is a difference. What do you think it is?

I found couple possible explanations

First explanation is that with present continues this sentence means predictable behaviour, with present simple it is a habit in general.

Another possible explanation. Present continues in this sentence means that speaker describes her habit in a negative way. Present simple usage doesn't entail anything negative.

You are right, Su.Ki. thank you. I changed to beginner.

Peachey has a point, Oleg.  You describe your level of English as B2 or Intermediate. Anyone with an intermediate level of English should have at least some idea about the difference between the present simple and the present continuous.