The division operator / divides the numerator by the denominator, generating an error in the case of a division by zero. The error can be intercepted by ISERROR and IFERROR functions. However, several products do not show the error, returning positive or negative infinity depending on the sign of the numerator, or NaN in case of 0 / 0.
The DIVIDE function is different because it provides an alternate result in the case of a division by zero.
Any argument passed as a string is automatically converted into a number.
The following two expressions are equivalent.

20 / 4
"20" / "4"