As adjectives the difference between ebullient and ardent

is that ebullient is enthusiastic; high-spirited while ardent is full of ardor; fervent, passionate.

As nouns the difference between reward and reinforcer

is that reward is something of value given in return for an act while reinforcer is something that reinforces; something that strengthens a behavior.

As a verb reward

is to give (something) as a reward.

In obsolete terms the difference between factor and challenge

is that factor is a doer, maker; a person who does things for another person or organization while challenge is to censure; to blame.

As nouns the difference between factors and challenges

is that factors is plural of lang=en while challenges is plural of lang=en.

As verbs the difference between factors and challenges

is that factors is third-person singular of factor while challenges is third-person singular of challenge.

As a verb conjecture

is .

As an adjective factual is

of or characterised by or consisting of facts.

As nouns the difference between participation and study

is that participation is the act or process of participating while study is a state of mental perplexity or worried thought.

As a verb study is

to revise materials already learned in order to make sure one does not forget them, usually in preparation for an examination.

As a proper noun lemon

is .

As a verb cars is

to break.

As verbs the difference between rust and tarnishing

is that rust is to grow while tarnishing is .

As a noun tarnishing is

the act by which something is tarnished.

As a verb repercussions

is .

As a noun outcome is

information, event, object or state of being produced as a result or consequence of a plan, process, accident, effort or other similar action or occurrence.

As nouns the difference between contrariness and contradiction

is that contrariness is the state of being contrary while contradiction is (uncountable) the act of contradicting.