Scored 680 on Manhatten Test 1 :- need 720 Plz help

Hei All I have just taken the Manhattan Cat 1 scored 680(Q 45, V 37 ) , also I have given the Princeton review Cat 1 :- 620 (Q43, V 33 ) Can someone pls explain the discrepancy of 60 points . Which one is the real indicator of the actual GMAT level . I am planning to give Gmat is another one month a...