The fourth option is equivalent to the third, GET usually is a symlink to lwp-download. BUT note that during installation of LWP you're asked if you want the GET/HEAD/POST symlinks, and you (or the OP) could choose to answer no to avoid program name clashing, expecially for the HEAD command in filesystems that do not support case distinction.

A typical case is in the cygwin environment when it lives in a FAT32 filesystem: in this case, HEAD and head (which gives you the first lines in a file) would clash and you wouldn't get what you want. To be "portable" in the examples, I'd always use the lwp- beginning commands.