"Daisy" (Daisies = plural) is a common generic term and can refer to any of a large group of different plants that share similar general characteristics - much in the same way that a group of plants are called "herbs".
The portfolio of Daisies is not fixed and covers a multitude of plants which vary from country to country. Simply because their flowers appear similar, people refer to them commonly as a Daisy if they do not know the correct botanical name.
Some common examples are:
Common Daisy - Bellis perennis
Oxeye Daisy - Leucanthemum vulgare
Shasta Daisy - Leucanthemum X superbum
Crown Daisy (Garland Chrysanthemum)- Chrysanthemum coronarium / 4 other names
Livingstone daisy - Dorotheanthus bellidiformis (formerly Mesembryanthemum criniflorum)
There are different types of flowers, each with their own unique genetics that sets them apart from others. Each of these has a "botanical name", which identifies, classifies and separates it from other plants.
While there is an entire classification system for each plant most horticulturists, botanists, landscapers and farmers simply use the last two or three parts of the naming protocol - the Genus and Species.
The use of the Genus and species can be compared to identifying a person by his surname and then his forename.
The botanical name of the Shasta Daisy is Leucanthemum x superbum. It is a hybrid of several daisy species.
The botanical name for colocasia is Colocasia esculenta.
The botanical name of Gongura is Hibiscus sabdariffa.
The botanical name of Marconi wheat is Triticum aestivum.
The botanical name for periwinkle is Catharanthus roseus.
Helianthus is the botanical name for the Sunflower.
The botanical name for firecracker flower is Crossandra infundibuliformis.
Tabernaemontana coronarea is the botanical name of tagar flower.
Corpse flower. The botanical name is Amorphophallus titanum.
Bougainvillea glabra
The Goldenrod (Botanical name: Solidago) has gold in it.
botanical name for it is Belamcanda chinensis
Chrysanthemum indicium is the botanical name for the Godavari flower. The flower is commonly known as a chrysanthemum. The name for the chrysanthemum in Nepal is Godavari flower.
Nymphaea Caerulea
Ulmus (botanical/ genus name of Elm trees)
The botanical name of sheesham tree is Dalbergia sissoo. It is a species of flowering tree in the pea family, Fabaceae.
Depends what your nation is. This is an international website. Re-ask the question with the name of your country.