-ant creates adjectives, -ance creates nouns.

adjectivenounagent noun
abundant
adamant
ambulant
arrogant
brilliant
buoyant
compliant
confidant
conversant
defiant
deviant
discrepant
distant
dominant
dormant
elegant
errant
exorbitant
extravagant
exuberant
flagrant
fragrant
flamboyant
hesitant
ignorant
important
incessant
indignant
itinerant
jubilant
luxuriant
malignant
mutant
observant
petulant
pleasant
pliant
poignant
pollutant
predominant
pregnant
protuberant
radiant
rampant
redundant
relevant
reliant
reluctant
repentant
repugnant
resistant
retardant
reverberant
significant
tolerant
trenchant
triumphant
unpleasant
vacant
valiant
verdant
vibrant
vigilant
abundance

ambulance
arrogance
brilliance

compliance


defiance
deviance

distance
dominance

elegance

exorbitance
extravagance
exuberance
flagrance
fragrance
flamboyance
hesitance
ignorance
importance




luxuriance


observance
petulance




predominance

protuberance
radiance


relevance
reliance
reluctance
repentance
repugnance
resistance


significance
tolerance




valiance


vigilance
accountant
appellant
applicant
aspirant
assistant
attendant
celebrant
claimant
cohabitant
combatant
commandant
consultant
contestant
continuant
decongestant
defendant
defoliant
deodorant
dependant
descendant
desiccant
disinfectant
entrant
immigrant
informant
inhabitant
interactant
litigant
lubricant
merchant
migrant
militant
mordant
occupant
participant
peasant
pedant
propellant
protestant
refrigerant
registrant
ruminant
savant
servant
stimulant
supplicant
sycophant
tenant
termagant
truant
tyrant
vagrant