He was a pilot, not a platoon leader.
( He ( ( was ( ( ( ( a pilot ) , ) not ) ( a ( platoon leader ) ) ) ) . ) )
(ROOT (S (NP (PRP He)) (VP (VBD was) (NP (NP (DT a) (NN pilot)) (, ,) (RB not) (NP (DT a) (NN platoon) (NN leader)))) (. .)))
He was no platoon leader, but a lowly pilot.
( He ( ( was ( ( ( ( no ( platoon leader ) ) , ) but ) ( a ( lowly pilot ) ) ) ) . ) )
(ROOT (S (NP (PRP He)) (VP (VBD was) (NP (NP (DT no) (NN platoon) (NN leader)) (, ,) (CC but) (NP (DT a) (JJ lowly) (NN pilot)))) (. .)))