"<br>,</br>,<br/>,<br />" All are same, why?

Answer 1

Yes, because some tags don't have closing tags, you can use <br/> or <br>.

also on <img/>.

Answer 2

Some HTML Tags do not have Closing Tags.
Why?
Well... we do not know. The Creators never outlined the proper reasons...
But just think of it as:
"
If it's a simple thing, then we don't need double tags!
"
Hence, 'New Line' = <br> or </br> or etc.