Multilingual is built into Drupal and as far as I am aware, it's a plugin for Wordpress.

Complex permissions/access control is another area where Drupal is much stronger.

And overall, the more complex the requirements are , the more likely Drupal will be the answer. Wordpress leans very heavily towards "here, install this, it'll work, you can tweak it and that's about it". Drupal gives you a gigantic bucket of LEGO. In other words, although it's a bit of an exaggeration but not badly, with Wordpress you start from a working website and there's only so far you can walk from that point. With Drupal, you need to walk quite a bit in the first place to get a good website but there's just no end how far you can walk.