It is hard to tell elephantinum from didieri, there are floral differences but I can't remember exactly. If I remember correctly, both plants are relatively small, but the largest a didieri will get is right at the smallest average size for a blooming elephantinum. Elephantinum flowers are over 2 1/2 inches, I couldn't find a measurement for the elephantinum nectary. Leaves can be longer than for inches especially on a mature specimen. If the flower Eyrthrone posted is over 2 1/2 inches, but less than 4 inches it might be elephantinum. My Angraecum virquieri flowers are pretty big, I'd say over 4 inches, and once open a few days have a strong copper color to petals and sepals.
Didieri will remain a smaller plant with leaves less than 4 inches long, and roughly 2 inch to 2 1/2 inches flowers with a nectary over 5 inches long. Note that the didieri top flower size is 2 1/2 inches. Many times a young didieri the flowers are bigger than the spread of a pair of leaves, the plant can hide behind its flower.