is a specific kind of: bush, shrub.

is a broader term that covers: Crataegus apiifolia, Crataegus marshallii, parsley-leaved thorn, parsley haw | Crataegus biltmoreana, scarlet haw | blackthorn, Crataegus calpodendron, Crataegus tomentosa, pear haw, pear hawthorn | cockspur hawthorn, cockspur thorn, Crataegus crus-galli | Crataegus aestivalis, mayhaw, summer haw | Crataegus laevigata, Crataegus oxycantha, English hawthorn, may, whitethorn | Crataegus monogyna, English hawthorn | Crataegus coccinea mollis, Crataegus mollis, downy haw, red haw | Crataegus oxyacantha, evergreen thorn | Crataegus coccinea, Crataegus pedicellata, red haw.

is a member of: Crataegus, genus Crataegus.