the first bar is the common old c major scale beginning in the third fret of the a string and played over 3 strings (A,D & G). the second bar shows it beginning at the eight fret of the e string and played over 3 strings also (E,A & D). the third bar is a hybrid of both and shows how to play the scale over four strings (E,A,D & G).

the difference is that you are beginning this hybrid with your left hand pinky finger at the root note, then to your index finger for the second note. for the seventh note you then need to move your left hand down a fret so that your index finger falls on fret 4 of string G and for the eight note your middle finger falls on fret 5 of string G.

C Major

C major

C Major