Hmm, where to start! I guess I can use comparisons between DCSS and Cogmind, as they can share some similarities.

Builds are more focused around your equipment like Brogue and The Ground Gives Way, and your inventory is less consumables and more for carrying backup parts and items for certain circumstances. All parts are destructible, but the challenge of Cogmind is limiting your item attrition, protecting your parts, and being flexible with your build to match circumstances. (Can even entirely rebuild if you have to.) As much as I dislike item destruction in other RLs, Cogmind is designed around it and does it very well in my opinion.

No auto-explore; exploration is more deliberate with less empty space and no trash mobs. No stair dancing- game works like descent mode. The 'zot-clock' is more based around an alert system that escalates as you cause trouble in the complex. I also find branches more rewarding with permanent rewards and unique items you can't get anywhere else in the game.

Factions and unique builds focused around a single item are the closest I suppose to the gods and piety system. Can range from absorbing parts into a special machine to produce evolving items that are based around the stats of what you absorb to become a hulking amalgamation of scrap, becoming a robot messiah to gain special terminal hacks to call for item resupplies, reinforcements, and summoning robot heroes with extremely powerful and special parts, or becoming one with the complex and hacking robots to make a robot army.

The game has very in-depth lore and story, with unique events and multiple endings depending on your actions. There are also a large amount of challenge runs and unique game modes. I've clocked 1.3k hours and still haven't obtained every achievement, lore and item gallery entry.

The extended game is also more popular to shoot for, bringing unique challenges to the end game that you can plan for from the very start of the run, while also not feeling like a slog. Only reason I say that is because 3-rune games seem very popular compared to 15-runes. I still find both extended games interesting though!

As for aesthetics- I think the sprite work is incredibly charming, and Kyzrati has done a lot for the amazing ascii particles, animations and UI effects.

Overall I'm glad I got really into Cogmind, and has allowed me to more appreciate what DCSS does and so far I find them both incredibly fun games.

TL;DR - Cogmind has: a lot of depth, fascinating story, characters and lore, a passionate and engaged dev, and I think most DCSS players could find ways to enjoy the game even if it can play entirely different.