I dont want fan wars anymore so avoided the name
and you mentioned all the difference here. An international fan of JMa had mentioned what you have said here in her IG. Its like everyone is noticing same thing about him 
@Step Well I've seen a couple of bts clips of James with his 1st n'ek (I guess we're avoiding names here lol) and they seem to be playful and comfortable around each other but it's very different from how he interacts with Kim. With Kim, he's calm and collective but at times shy and reserved but somehow not distant from his affection to her. He's attentive in a very gentlemen-like way without stepping overboard. He glances at her to make sure she's alright and only take action when he sees she needs help. In the fanvid there's a moment when the performance was done and everyone was existing the stage, as Kim walked down the stairs, James' behind her extended his hand cupping the air around her elbow's area to make sure if anything happens he's there to catch her from her fall. It's these little moments that makes him seems so genuinely protective and attentive towards her in the most timid way. With Kim, James feels like a man despite the fact that he's a year younger than her. I find it cute.