music and melodies

Is there a difference between these two?

What about a song? For me… to simplify things, I think about music as a whole. A composition consisting of multiple players making something together.

I think about melodies as something that can be expressed by just one thing, one instrument or even through use of vocals.

But then songs and notes are somehow left in the dust as how to explain those? 

Can you share your thoughts? Let us know below!