Hi,
Check out the Natural History Museum definitions:
English bluebell :
The flower spike is usually 20-50cm high, with the flowers arranged in a raceme that droops or nods distinctly to one side. Each raceme usually has between 4 and 16 flowers.
Each flower has two linear-lanceolate bracts, one usually longer than the other, at the base of the flower stalk. The flower stalk is normally 3-10mm long. The flowers hang down to one side of the main stem. The flowers are usually deep violet-blue but paler blue forms (rarely white and very rarely pink) do occur. Each flower is made up of six petals that are fused together at the base to form a narrow straight-sided bell. Flowers are normally 10-28mm in diameter and each petal is usually 14-20mm long. The petals are usually rolled back.
http://www.nhm.ac.uk/nature-online/british-natural-history/survey-bluebells/bluebell-identification/native/index.htmlSpanish bluebell:
The flower spike is usually 20-50cm high, with the flowers arranged in a raceme that is stiff and upright. Each raceme normally has between 4 and 20 flowers that are usually attached to the main stem on all sides.
The flowers usually point outwards. Each flower has two linear-lanceolate bracts, one usually longer than the other, at the base of the flower stalk. The flower stalk is normally 10-20mm long. The flowers are usually pale to mid-blue (sometimes white or pink). Each flower is made up of six petals that are fused together at the base to form a wide-open bell. Flowers are normally 15-25mm in diameter and each petal is usually 15-22mm long. The petals are widely spreading and are usually not rolled back.
http://www.nhm.ac.uk/nature-online/british-natural-history/survey-bluebells/bluebell-identification/hispanica/index.htmlHope this helps. :happy:
[Edited to add links to avoid plagiarism / copyright issues.]