To understand both, look at the linking verb.

Linking verbs include:

to be (is, was will be, have been, etc.)

remain

seems

resembles

become

Note that the word nominative really means just noun, so in looking for a nominative you’re looking for a noun.

When you see any of these verbs in any tense or conjugations, you’re probably going to see a predicate nominative or a predicate adjective. And probably most of the examples you deal with will be forms of these verbs, or verbs that are close in meaning to them.

Ex:

She is pretty. (Pretty is a pred. adjective. It describes her)

She will be a star. (Star is a pred nominative. Simply because star is a noun, hence nominative.)

The barn is red. (Red is a pred adjective. All colors are adjectives: they describe. )

He seems nice. (Pred adj. Nice is a descriptive word, that is, an adjective.)

They remain friends. (Pred nominative.Friends is a noun.)

A noun following the verb will be a predicate nominative. A descriptive word will be an adjective.

The barn resembles a house. (pred nom)

He became a salesman.

He might become angry. (pred. adj.)

With these linking verbs, the subject is more or less EQUAL to the noun that follows or the adjective.

These are NOT the sort of verbs that take a direct object, such as.

She hit the ball.

She is not equal to the ball. She begins an action and the action happens to the ball. The ball is a direct object and NOT a predicate nominative.