Why does illustration look like illustration?
I've taught myself to paint over the last ten years or so using everything from watercolours to oils, and I'm not bad. I've now come to a place where I understand that the style I most want to produce is a more illustrative look. I'm attaching examples of two pieces that very well demonstrate what I mean. The first is a comic book panel from "Onibi" by Atelier Sento, and the second is two sketches by Hiromasa Yonebayashi for "The Secret World of Arrietty" by Studio Ghibli. They're representational, but clearly look like illustration or animation.
Here's my dilemma; even after months of poring over works like these and doing many studies of them (which end up looking quite similar), I still can't get my head around what makes them look like illustration as opposed to realism, so when I try to produce something of my own, it's still looking closer to realism (the third attachment, the lighthouse, is a recent example).
Where am I going wrong? All I really need is a clue of what I should be trying to adjust in my work. Are my lines too straight? My colours too intense? Too much detail?
Sorry, I realise that when talking of style it's easy to get into "how long is a piece of string" type arguments, but at this point I'm open to any insights as to how to move closer to the style I adore so much. (There are plenty more examples of recent work in my Instagram if that helps - link in sig).