Are requirejs And require the Same?
As of RequireJS 2.1.15, require and requirejs in the global space are indeed "exactly the same", as can be evidenced by this test you can perform in the console:
> require === requirejs
true
That the test returns true tells you they are the exact same function object. They are not two functions that happen to have similar or identical code. They are the same object, period.
Note, however when you execute define(['require'], function (require) { The require passed to the function is normally different from the global require.
Should You Use require or requirejs?
It depends. RequireJS is an AMD loader but it is not the only loader in town. If you want to write code that conforms 100% to the AMD spec, so that someone using your code can use whatever loader they want without having to modify your code, then you should use require at the global level, because requirejs is specific to RequireJS. Another AMD loader won't define it. The AMD spec defines require but not requirejs.
If you are loading something else that defines a global require then you have to use requirejs at the global level to avoid conflict.
Inside a module, always use define to obtain a reference to require. You should do this quite irrespective of whether there is a conflict in the global space.