The "Normal" style prints both melody notes and chords, each occupying the same space, like this:

The Condensed style prints melody notes that are not accompanied by chords in a single line.  The keyboard is not shown.  Therefore it prints more  song content per page.  This style works best for songs in lead sheet music style as found in fake books because each bar usually consists of one chord name and several melody notes.  It looks like this (same song as above):

To further help with identifying keys, the Condensed style follows this convention:

1)  if the corresponding key is a white key, the note is shown as an empty square

2)  if the corresponding key is a black key, the note is shown as an solid black square

3)  in either case if the melody note is a tied note, the color of the square is in a lighter shade of gray.

The figure below illustrates this.  Rhythmic value are displayed on the right margin.