One is certain and the other in uncertain.
antonym: uncertain, unsure
uncertain
uncertain
Uncertain
Uncertain.
Not certain; not having certain knowledge; not assured in mind; distrustful., Irresolute; inconsonant; variable; untrustworthy; as, an uncertain person; an uncertain breeze., Questionable; equivocal; indefinite; problematical., Not sure; liable to fall or err; fallible., To make uncertain.
Certain and uncertain
know
The most certain thing is that change is inevitable. Nothing stays the same forever and everything is subject to change. The most uncertain thing is the future. We cannot predict what will happen or how things will unfold, making the future inherently uncertain.
Curtain, uncertain, certain, hurtin
certain Confident