I’m pretty naive in the subject, except for the fact that Easter lilies are my favorite. Wait, I mean Casablanca. Actually, I just love white strong scented lilies! : )

I agree with you I like the white fragrant lilies the best.
“Casa Blanca” is the name of a cultivar or clone of an Oriental hybrid Lily (Lilium hybrid). These are crosses between several species lilies from the Far East.
The Easter lily is a Lilium longiflorum a species from Japan & other islands nearby.
Other very fragrant white include Lilium regale and Lilium candida or the Madona Lily
http://www.brecks.com/product.asp_Q_pn_E_67366
http://www.bdlilies.com/l8013.html
Oriental hybrids like ‘Casa Blanca’ were crossed from Far Eastern species: L. auratum, L. speciosum, L. nobilissimum, L. alexandrae, L. japonicum, L. rubellum The Asian cultures have a long history of cultivating crosses between lily species so the exact crosses that led to the modern plants are not all known.

Hybrid Divisions – Modern hybrid lilies are grouped according to their parentage into nine divisions. The names of these divisions give a broad indication of the origins of the hybrids.
I Asiatic hybrids
II Martagon hybrids
III Candidum hybrids
IV American hybrids
V Longiflorum hybrids
VI Trumpet hybrids
VII Oriental hybrids
VIII Miscellaneous hybrids
IX Species ~ 100