Q: Is adoration a liturgy? devotion? both?
A: Adoration may take place inside a liturgy or as an exercise of devotion. If exposition of the Blessed Sacrament has happened, then adoration is part of that liturgy.
But if people are making a visit to the unexposed Blessed Sacrament in the tabernacle on their own, that is a devotional exercise.
The act of adoration within the liturgy may appear devotional, but it is part of the structure of the liturgy of exposition.