Per Wikipedia:

Calendula (/kəˈlɛndjuːlə/) is a genus of about 15–20 species  of annual and  perennial herbaceous plants in the daisy family, Asteraceae that are often known as marigolds. They are native to southwestern Asia, western Europe, Macaronesia, and the Mediterranean. Other plants known as marigolds include corn marigold, desert marigold, marsh marigold, and plants of the genus Tagetes.

The genus name Calendula is a modern Latin diminutive of calendae, meaning “little calendar”, “little clock” or possibly “little weather-glass”.[5] The common name “marigold”, a contraction of “Mary’s gold”[5] refers to the Virgin Mary. The most commonly cultivated and used member of the genus is Calendula officinalis, the pot marigold. Popular herbal and cosmetic products named “Calendula” invariably derive from C. officinalis.

Interestingly Wikipedia has two articles about Calendula, the second is here

I found this tidbit on a website about gardening as I tried to understand why a novice like me was struggling to see the difference between Calendula and the Daisies.

Calendula flowers (Calendula officinalis) are commonly known as pot marigolds, which can lead to confusion at the garden center. Although their names are but one word off, those three letters belie a bevy of differences.

For one thing, these annual flowers differ vastly in appearance. Marigolds (Tagetes spp.) have shorter, compact petals and thinner leaves. Calendula flowers feature longer petals and rounder, wider leaves. Although both plants are part of the daisy family, calendulas look more like daisies.