What changed?
( What ( changed ? ) )
(ROOT (SBARQ (WHNP (WP What)) (SQ (VP (VBD changed))) (. ?)))
What was different?
( What ( ( was different ) ? ) )
(ROOT (SBARQ (WHNP (WP What)) (SQ (VBD was) (ADJP (JJ different))) (. ?)))