Aggregate Fruits appear to be one fruit but they are actually composed of many tiny fruits which develop from the Many Carpels of One Flower with an Apocarpous Gynoecium.

The Gynoecium of a Rubus flower is composed of many Simple Carpels. Each becomes a fleshy fruit (Drupelet).

The Fruit of Blackberry (Rubus) is composed of many tiny Drupelets. Each "Fruitlet" is the product of one Carpel. Consequently, this is an Aggregate Fruit.

Noni Flowers are tightly spaced.

The fruit of Noni (Morindra citrifolia) is actually the fruit of Many Flowers. It is thus a Multiple Fruit!

Each Flower produces a Fruit!

The Mature Fruit has shed its flower parts but it still represents Many Fruits!

One Flower & Many Carpels = Aggregate Fruit

Many Flowers = Multiple Fruit