Different driveline angle on balancer to output shaft?

Why would I be getting different readings on driveline angle between the balancer face and the trans out put shaft? Balancer shows -2* @ 88.1 but the output shaft shows -3* @ 87.0. WTH don't I understand. Which is correct?

IMG_20190803_120714295.jpg

IMG_20190803_120630121.jpg