Question about BeautifulSoup parameter

Does the argument that the function

  soup = BeautifulSoup(var_1, 'parser')

  receives have to be in binary text? Should I use

 var_1 = response.content

 , or can it be text and I use

 var_1 = response.text

?

I have compared both and found that they are the same, but I would like to know if this equality holds in all cases.