@w8emv Delta Chat has channels (1-to-many like on Telegram), Signal doesn't
Signal is centralized and hence much more easy to block, while Delta Chat can even work in intra-net and mesh networks
Delta Chat can use several servers "relays" at the same time, do you remember that downtime with signal when #amazon or #cloudflare are down?? with Delta Chat if one of your relays go down you can keep chatting using the others (ex. people manage to use Delta Chat in Iran, Russia and China despite the strict network firewalls, if you go on vacations to China Signal will not work, Delta Chat will)
Signal doesn't support using the same account in multiple phones, and multi-device with desktop is weak and still depends on the phone, with delta chat you can have several devices at the same time and it is super easy to add a second device
each device in Delta Chat works as an incremental automatic full backup, while in signal you have to upload backups to some cloud and eventually pay for it when the backup is too big
in Delta Chat you can have several profiles, as much as you like, easily separate your work profile (with more serious avatar and name) from your family profile where you can use more informal name and avatar etc
you don't need phone numbers or any private data to use Delta Chat, onboarding is super easy, no SMS codes, no solving CAPTCHA like on Signal
No strangers can discover you and send you spam or fishing in Delta Chat same for your family members, so it is a safer space for family chat
#DeltaChat has offline-first in-chat mini-apps like games, collaborative text pads, checklist, shopping lists and other tools (all end-to-end encrypted without any 3rd party service hosting such apps, they live in the chat and only chat members can access them)
in Delta Chat you can save messages in a "Saved Messages" chat, #signal also has "Note to Self" but what is superior in Delta Chat is that you can also jump from the saved/bookmarked message to the original message and see it in its chat context, in Signal it just forwards a copy of the message to the "Note to Self" chat
and more, but this post is too long already