Arcane/Delta are compatible/interoperable with each other, one of the DC devs (the aforementioned adb) is the dev of Arcane and it's kind of his testing grounds, it has a few extra features like extra themes, markings on the official chats to help prevent scammers, and turning off accts at the profile select screen.

But tbh I went back to DC proper myself last week just because I didn't get that much benefit (didn't like the themes over the OG, only use one acct so far and it uses no battery so no need to switch it off, but I did like the badges on the saved/device chats and hope that makes it into the official). Plus the official has the experimental "channels" now that I wanted to play with, and you can enable "debug calls" now so I don't need Arcane for that anymore. Still love adb and he's still working on Delta too (and you can message him using either, his contact details are on arcanechat.me lol, and he's heavy on the DC forum, which you can log into using DC)!

Basically "same thing, try both, you can 'export backup' from say Delta and 'add as second device>import from backup' in Arcane and be logged into both if you want." I did that for a day or so while deliberating.