My Wife

A Naat is a song specifically for the love of the Prophet (saw)
A Hamd is for Allah (swt)
And Nasheed is the word describing an Islamic song including the 2 above.

Now the main thing here is that it is poetic verses in song but without the use of musical instruments. That is what is Islamically allowed from what I have heard.

Not that I don't listen to music. God knows I do!