So, if you accept this definition, then anyone who is saved in the celestial kingdom (even people baptized but not endowed, which kept their baptismal covenants) will have overcome spiritual death as they will be literally in the presence of God. Anyone who achieved the highest level within the celestial kingdom (entered into and kept the new and everlasting covenant of marriage) would be exhalted.
I once saw a comparison between Mercy and Grace. It said Mercy is when a punishment that we deserve is withheld. Grace is when a reward that we do not deserve is bestowed. I really like this explanation.
I think that’s a great “difference between” question.