Similar designs, different outcomes . why?

Yesterday i made two builds, specific for PVE.

The objective it’s to lower the work overload and ease the grind ( raids). And i’m testing new stuff, tempuras, giving a second chance to triggers ( the first time i got them i sold them immediately to found other stuff ).
So, the first thing was the prototype of this one. ( this is the final version)

But then i wanted to improve it, make it tougher, so i did this.

So, you can see it’s basically the same design, the same front, the same parts.

But with a big difference ( among others).
It turned out that the first build can take a bigger beating than the second one.
My main complain is with the second build i always lose the first Caucasus sooner or later and with the first one the survivability it’s much better.

One of the reasons i can think, is with the second build the mass it’s higher so the bots must aim higher than with the first build and instead the plows catching the shells/blast damage , The frontal Caucasus is the one catching all of that.
What more could it ?
The second build has more everything but yet, the first one is tankier and it’s rare i lose anything with it.
Sometimes the front it’s intact but missing the gun (second build.
Your thoughts?

bots ALWAYS aim for the cabin, but in rare cases they will aim for your weapons. the ones with auroras are notorious for that. but when i build a vehicle i NEVER put my weapons in the way of fire because i can lose them. in rare cases i can lose my weapons to, but more often then not i never lose them… except if the ai is cheating which it does sometimes…
i have a beefy build to but also in raids the difficulty spikes artificially and its a bit of a pain to deal with. what do i mean? well its like this basically:
you can go into a raid and get through it with 1/4 of your life left one raid. then you can go in another raid and the enemies just do absurd amounts of damage and only target you.
ive had this happen before where id go into a raid and at the very beginning id lose both my plows and 3/4 of my hp just from the beginning bots! but in the previous raid id have both my front plows and full hp when i got the beginning bots done.
its like the bots damage multiplies harshly JUST to force you to use a revive in the raid. and it doesnt stop until you die. when you respawn the damage goes back to normal for them, its very weird how it works.
i dont think its your build, its the bots.
this isnt just in raids either its also in pve as well. sometimes cannon damage will be absurdly high and the explosion damage does far more damage then it should even knocking off my weapons in 1 or 2 shots when they are mounted behind my cabin.