Why does Spotify have a second pause button?

I noticed Spotify has a big green "pause"/"play" button, even though there already is one in the controls on the bottom.

I have been using Spotify for several months and never even paid any real attention to it and it feels really useless to me. When clicked it literally just pauses the track playing and changes its text to "play".

Here's a screenshot:

Is there any reason for this button existing? Does the green button have some underlying functionality I am not seeing?