They are identical as described in the official Python 2.7.15 documentation.

os.remove(path):

Remove (delete) the file path. If path is a directory, OSError is raised; see rmdir() below to remove a directory. This is identical to the unlink() function documented below. On Windows, attempting to remove a file that is in use causes an exception to be raised; on Unix, the directory entry is removed but the storage allocated to the file is not made available until the original file is no longer in use.

Availability: Unix, Windows.

os.unlink(path):

Remove (delete) the file path. This is the same function as remove(); the unlink() name is its traditional Unix name.

Availability: Unix, Windows.

When using pathlib.Path file access in Python v3.4 and higher

While the question specifically asks for the os module file removal, the latest versions of Python have another option for removing files that may be an alternative.

Direct Answer - use pathlib.Path.unlink()

• Note: pathlib.Path.remove() does not exist

When using the pathlib module for file access, use pathlib.Path.unlink() to remove files.

The Path.unlink() method is a replacement for both os.remove() and os.unlink(). It is executed directly on a Path object, rather than being passed the location of a file through a string argument.

More details

Starting in Python v3.4 the pathlib builtin module is available to handle file access in an object-oriented manner. I believe a separate package is also available via Pip for older versions of Python.

With pathlib, you create folder and file objects that are of the Path class. The related method of removing a file has been consolidated to just unlink(). They do not have a remove() method (likely because, per shash678's answer, there is no difference, it's just an alias). This appears to be equivalent to the os methods of file deletion, other than the underlying means of specifying the file itself.

See Object Oriented file system paths, along with the table at the bottom that shows both os.remove() and os.unlink() map to Path.unlink().

In Python v3.8, a missing_ok argument was added to the Path.unlink() function. When *missing_ok* == True, an exception will not be raised if the file doesn't exist before trying to remove it.