Once upon a time a Grape Hyacinth was a Grape Hyacinth and if you wanted to be scientific you called them Muscari. These days things are little bit more complicated.
Pseudomuscari were separated into a subgroup of Muscari in 1935, became a sub genus in 1965 and finally gained the status of genus in their own right in 1970. Today (2022) they have returned to the status of sub genus.
A key characteristic, which sets them apart from their close Muscari relatives, is that the individual bell shaped flowers are not constricted at the mouth, but are instead, open.
The genus often have densely packed racemes of flowers which are most usually pale or bright blues.
As the flowers age from the bottom of the raceme, they take on deeper shades and loose the more obvious patterning.