What is the difference between a C$++$ struct and class?

Question $1$ options:

$1)$

A class cannot access functions from iostream.h

$2)$

A struct cannot access functions from iostream.h

$3)$

In a struct the default accessibility is public, whereas in classes the default is private

$4)$

There is no difference

$5)$

A struct cannot have private members

$6)$

None of the other options

$7)$

In a struct the default accessibility is private, whereas in classes the default is public