How does this work? What’s the difference? Do troops attack the traps first or the wall? Thanks!
Wall DEF is the base of the wall level while trap DEF is the units you make to go on it. Even without traps, a higher Wall DEF means your wall is stronger. You can then also make traps to go on it. Those who are constantly shielded don't usually bother as they think wall DEF is useless as the wall falls without all traps being used anyway. It's not something you should invest on straight away although you can go for it
Wall defense is the defense of the physical wall. The enemy has to break down the wall to get to the troops behind it.
Trap defense is the amount of defense traps have, the greater the defense, the more sturdy they are when being attacked by the enemy.
I'm not sure on the order, or if there is an order, on which gets attacked "first". What I can tell you is that traps will absorb damage from the enemy keeping your wall standing longer.