What is the difference between ( http:// ) and ( https:// )

The main difference between http:// and https:// is: it's all about
keeping you secure.

HTTP:// stands for Hyper Text Transport Protocol,
Which is just a fancy way of saying it's a protocol (a language, in a
manner of speaking)
for information to be passed back and forth between web servers and clients.
The important thing is the letter "S".
This is what makes the difference between http:// and https://.
The "S" (big surprise) stands for "Secure".
If you visit a website or web page, and look at the address in the web
browser, it will likely begin with the following: http://.
This means that the website is talking to your browser using the
regular 'unsecured' language. In other words, it is possible for
someone to "eavesdrop" on your computer's conversation with the
website. If you fill out a form on the website, someone might see the
information you send to that site.

This is why you never ever enter your credit card number in an http:// website !

But if the web address begins with https://, that basically means your
computer is talking to the website in a secure code that no one can
eavesdrop on.
You understand why this is so important, right?
If a website ever asks you to enter your credit card information, you
should automatically look to see if the web address begins with
https://.
If it doesn't, do NOT enter sensitive information like a credit card number.