There was an interesting comment from cwalton about warcaster design. Even if the
warcasters come from the ranks there should be something about them, some detail
or other thing that makes their silhouette stick out.
It's probably why they went with smokestacks for most of the warcasters.
This is just me guessing from here on out, but:
Stryker with the funky hair.
Kreoss with a two handed flail.
Original Skarre is awful.
Shambling Magnus.
Ashlynn's fencer look.
Harbinger.
Old Witch.
etc.
If you are confusing these models with the rank and file (even regular Caine) I think that
has more to do with unfamiliarity than anything else. It's like someone who doesn't play
40k regularly looking at a table and mistaking a sergeant for your captain. Or thinking
that heroic space marine x is just another generic leader in powered armor.