A shrub rose looks shrubby. They usually have "single" roses (roses with 5 petals) (I think) and are usually shorter plants. A grandiflora rose has blooms that are usually a single bloom to a cane and are tall & leggy. Think of a florist rose. A floribunda has LOTS of blooms on a single cane, kinda like an instant bouquet.
Grandiflora - "Octoberfest"
Floribunda - "RedGold"
Shrub - "Kordes Brillant"
Of course I could be 100% wrong with all of this, too.
But that's how *I* remember them.
