From what I heard Tieflings have infernal heritage in themself.
But they are half non-devil, just like a Cambion actually.
° But Tieflings feel no loyalty to the nine Hells.
° Cambions on the other hand do.
Seems like Cambions are half-breeds who try to live between fiends ... and so they need to act as one (as much as possible).
And Tieflings are half-breeds who try to live between humans ... and so they need to act as one (as much as possible).
Or Cambions ar simply "a little more fiend than a human" and Tieflins on the other hand "a little more human than a fiend".