It may help to straighten out some terminology. Loved is always a past participle. That's because the past participle of a regular verb adds the suffix -ed to the regular form (i.e., the form used in the infinitive), with the proviso that the suffix replaces a final e. This means that past participles are always verb forms.
Past participles have a role in the predicate of indicating tense and voice:
- With the auxiliary have for the present perfect tense ("I have always loved you.")
- With the auxiliary had for the past perfect tense ("I had loved you before I hated you.")
- With the auxiliary forms of be for the passive voice. ("You are loved by me.")
Past participles have roles outside the predicate. They can modify nouns. Consider Evelyn Waugh's novel The Loved One.
They can head noun phrases. We don't use loved this way, relying on the now-defective verb belove, which appears only in the passive: "My beloved is like a gazelle...."
And they can appear in absolutes, associated with main clauses: "Loved by all, the general bowed to the cheering crowd."
With these uses comes a syntactic ambiguity. When the past participle (e.g, loved) follows the third person singular, present tense of to be (i.e, is), are we to interpret is as 1) an auxiliary forming the passive voice or 2) a copular verb followed by a nominative predicate? To rephrase, does
He is loved
mean that he is 1) an object of love or 2) a recipient of loving? That's a matter of semantics. We can only tell for sure if an agent is identified in a prepositional phrase with by:
He is loved only by his mother.
That's case 1), the passive voice, because we can transpose to active voice:
Only his mother loves him.