Before my elaborate explanation, I'll have to say my reply is solely based on much literature I've read and personal experience in raising them from seedlings.
Actually it's rather easy to distinguish wandae from others. The most distinct 'birth marks' that separates it form others is that this plant have 'fingers' covering the growth point (head). Both wandae and superbum have similiar coloration and veins pattern on their shield fronds. Wandae is still rare in M'sia and much sought after.
Below are some growth pictures of my above explaination.
Finger at the growth point giving protection from external factors.
Notice the veinings are very similiar in both wandae and superbum.
(Photo courtesy from Wanna.)
Although these few giants like superbum, wandae or holttumii have similiar colorations in their shield fronds, ie: blue green or silvery green coloration, grande always stay at green color. Fuzzy fine hairs are much shorter in grande to almost non existence. Pict. below is an example of typical coloration of shield frond for grande.
Attached picture below is a holttumii. Both wandae and holttumii have very similar coloration except for the fingers as explained earlier.
No fingers in holttumii
No fingers in superbum too.
These are some fine characteristic that separates them apart from each others. Ofcourse, they are much more easier to distinguish from each other like single lobe, double lobed, upper and lower lobed with fingers or without fingers among them.
Hope this helps.
AT