Eucharistic Adoration is the time people spend praying and adoring Jesus in the Blessed Sacrament.
Benediction is when we are given a blessing with Jesus in the Blessed Sacrament. (The word “benediction” comes from the Latin word meaning “blessing.”) The priest holds up the monstrance containing the consecrated Host, and we are given a blessing. (It is actually Jesus Himself giving the blessing, not the priest — visually demonstrated by the priest covering his hands with the humeral veil during the blessing.)
Often Benediction is preceded by a period of Eucharistic Adoration.