Granddad had seen something one night.
( Granddad ( ( had ( ( seen something ) ( one night ) ) ) . ) )
(ROOT (S (NP (NNP Granddad)) (VP (VBD had) (VP (VBN seen) (NP (NN something)) (NP (CD one) (NN night)))) (. .)))
One night, Grandfather saw something. 
( ( One night ) ( , ( Grandfather ( ( saw something ) . ) ) ) )
(ROOT (S (NP (CD One) (NN night)) (, ,) (NP (NNP Grandfather)) (VP (VBD saw) (NP (NN something))) (. .)))