What does ReaTune do as opposed to this program?

It does what you need, it tells you the pitch of the sound you provide. And it writes that to a MIDI track if you want. You sing a note in the microphone and it tells you what note that is. You can sing the whole song and have ReaTune convert it to a MIDI track for editing. Or you can have the plugin translate and audio track (isolated vocals, in example) to MIDI.