You can definitely see the parallels. The games are doing similar things in slightly different ways: you get a team of misfits, you put together their gear and weapons and trinkets, and you create a working team that exploits their collective strengths and hopefully covers their weaknesses, and the games intentionally want you to try and develop in such a way as to produce characters and teams that are almost exploits in themselves, asking you to enhance abilities/traits in such a way as to give you advantages that are almost broken, like making the most of Death’s Door as a Leper in DD, or using Berserk on a polearm-wielder in BB to get two attacks every turn instead of one. Proper character death, plus you have to juggle character health, money, etc
They’re not quite equal in terms of complexity, but DD is a leaner game; you get your team sorted out and you go, and apart from one or two quiet corridors, you navigate traps and fights and you get a dungeon done in half an hour, maybe? Assembling a team takes a couple of minutes, five at the most if you’re really juggling some accessories around? Whereas in Battle Brothers, your team can be up to a dozen in a battle, and your company can be up to 20 men, so while it’s not much more complex, there’s more to handle, and each character doesn’t have a set class; each recruit comes from a certain background which have different predilictions, but any of them can have a wide range of traits, and any of them can be given any perk.
So in this case, this character has Student (XP gain), Gifted (stat increase), Dodge (melee/ranged defence), Backstabber (bonus to having allies adjacent to the same enemy), Polearm mastery (polearms do more damage and use fewer action points), Berserk (AP on kills), Killing Frenzy (damage after kills) and Indomitable (take less damage). But this character could be an archer, or a front line fighter, or a dedicated polearm wielder. Whenever characters level up, they get to increase three stats.
You choose which three, so you can enhance any of their abilities you wish. So this mix of background/traits/perks/stats/injuries all intermixes and you can spec characters that do similar roles very differently. So it definitely is not as easy to play as DD, because there’s no class boundaries you can rely on.
BB’s world map is also a decent size, your party’s FoV is relatively small, so there can be a lot of travel time (in a bad week it can seem like you’re playing Caravan Guard Simulator), and the game isn’t scared to put you in a truly terrible position. I find DD you discover pretty quickly and sharply that your party isn’t cutting the mustard, you take a party wipe and go back to the drawing board. You can use that info to design a team you know can crack that encounter. BB isn’t scared to throw you into a battle you are very unlikely to win even with the ‘correct’ team (enjoy fighting 30 cannibal ghouls that power up whenever they eat a corpse! Hope nothing fucked up happens!), and it can also trap you in a death spiral where you win a battle, but all your equipment is damaged, all your characters are wounded, and you are miles away from anywhere. In DD you can get some breathing room with some easier runs, and while BB sort of has that, the main thrust of the design is that the world is carrying on without you, there are progressively more enemies, they are tougher, they’ll actively come looking for you, and while there are opportunities to get enemies to fight one another, and some easy targets, most of the time it’s up to you to keep your men happy, fed, paid, and alive, and if any of those things go wrong, you’re fucked. I had a game where I lost most of my team via running out of money. I had a game where all it took was a few key soldiers quitting because of dissatisfaction with the food on offer, and the rest of my team, late in the game, couldn’t cope with the battles.
BB has more freedom, but that’s also freedom to make mistakes and time spent for things to go wrong over a much longer timescale; I’ve found myself floundering in a late game with a team halfway capable, who go on to win a dozen battles badly, and that does make for a great story in retrospect, as your minor mercenary company has an outsize impact on the ongoing conflict and gets snuffed out as a result. That can be a really cool story to have, but experiencing it can feel harsh and frustrating, though I think a game like this should generate those feelings. If you’re a small mercenary outfit fighting in a conflict against a rising undead army, or an orc invasion, a lot of those stories are going to be the old tale of attrition in war. If you survive against the odds, it means a lot of people in the same situation did not. You can’t have an incredibly rewarding experience of surviving a harsh trial, if you don’t have a harsh trial in the first place.
BB’s focus is also more up to you. The world’s progression towards a crisis is inevitable, but your involvement in it is encouraged but not compelled; I had an orc invasion and I barely noticed. I was busy at the time trying to destroy a goblin city in an unrelated (but thematically connected) objective I decided upon. I took part in defending towns, raiding camps, hunting down war parties, etc, but I only took those orc contracts to fund my real work committing goblinocide. The amount of variance in the world and encounters and events and locations is staggering, I’m 290 hours in and still finding new stuff.
tl;dr DD is a dagger, short, sharp and pointy. BB is a warhammer, long, crushing and brutal. I like DD. I love BB.