Aren't these the exact same thing? Fail to see how they're different beyond semantics.
But that's the level of discernment I've seen about this the past 2 days? That's not particularly deep, is it?
It's nonchalance and not being interested in any reason why we might've seen our team perform like that. It's not the team that is "not arsed"- we're not arsed in judging them fairly.
The difference between those two, is that one explicitly means there was a CONSCIOUS DECISION TO MAKE NO REAL EFFORT- a cause. The other just means what it means- a lack of intensity- regardless of effort. It's just a symptom- not a cause.
There can be a lack of intensity for a variety of reasons- out of YOUR CONTROL. You could be tired and so you just cannot perform at a certain level, no matter how much you TRY.
You may suffer from jetlag, which prevents you from performing. We may be coming to the end of our run, which incurred a decent amount of effort from us, it could be the weather, or it could be brought on by training, preparation, lack of focus(another symptom), or diet, or whatever..
Any of this- but not for a lack of trying. You're trying but it just doesn't work.
But there is a difference- one is a decision/cause- the other is a consequence/symptom.
It's like when you've run/cycled a distance and getting tired... you're losing pace, and no matter how much you try, you just cannot make your legs go faster, you just cannot cycle faster. That would be a lack of intensity. That is certainly not because you're "not being arsed".