Are iostream and isostream.h same?

Question

Before I used iostream.h header file and didn't write using namespace std;
Now... I am supposed to use iostream header file and I even need to mention
using namespace std;
What's the difference between the two? Are they the same?
I am confused. Can anybody help me?

Answer 1

Please refer:
https://www.sololearn.com/Discuss/288609/?ref=app

Answer 2

Clarified. Thankyou