Export screen is not the same as the playback screen while editing.

Hello all.

I was going to export my video and noticed that it doesn't look the same as when it is in the 'edit' playback section. It fills up the full screen while in the playback section.

When it's in the export part it is smaller and has black vertical spaces on the right and left sides and won't fit all the way to the screen like it does in the playback section. 

I've attached screenshots of both views. TThe format I want is in the first picture but it doesn't end up that way when I go to export (2nd picture).

I was wondering if anyone knew how to fix this, any help is greatly appreciated.