neighborliness vs. neighbourliness
noticeableness vs. obviousness
nutritiousness vs. nutritiveness
noradrenaline vs. norepinephrine
neencephalon vs. neoencephalon
noninterference vs. nonintervention
neighborhood vs. neighbourhood
numismatist vs. numismatologist
nonachiever vs. underperformer
nephroangiosclerosis vs. nephrosclerosis