Yep, the way I think of them is:
Mentality is a way of giving your whole team instructions to attack or defend or do what comes naturally.
Arrows takes this to an individual player level. Red arrow motivates the player to get forward quicker/more eagerly when the team attacks. Blue arrows makes the player do similar except defensively....to get back quicker when defending. These extra motivations cause players to lose a bit more condition than if they wre left to their own devices.
A red arrowed player will still defend when the team defends as he normally would but might be further forward when opposition breaks so not as well positioned. Similarly a blue arrowed player will still attack.
Some people think its helpful to think of an arrowed player as being more advanced or withdrawn as if you have moved their position forward - I don't really subscribe to that but it might be true: I think its more he'll try to get more advanced or withdrawn quicker than he otherwise would have.
So, u set Team mentality in Orders and tweak individual players with arrows.
IMO. And I'm still new so what do I know.