Difference in cd.. and cd .. (Change Directory)

cd.. and cd ...

Basically, they are doing the same. But, who and why thought of changing it with space or without space? Why is there space and why there isn't space between cd and two dots?

C:WindowsSystem32>cd..

and

[bla/www/something/something]#cd ..

They are both the same. Why one has space, and another hasn't?

EDIT:

It's not duplicate of this question:.

Why does "cd.." work in the Windows command line?