When comparing Signal vs Discord, the Slant community recommends Signal for most people. In the question“What is the best team chat software?” Signal is ranked 2nd while Discord is ranked 8th. The most important reason people chose Signal is:
Signal uses an advanced end to end encryption protocol that provides privacy for every message every time.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Provides security and privacy
Signal uses an advanced end to end encryption protocol that provides privacy for every message every time.
Pro Free and open source
Signal is free and open source software, enabling anyone to verify its security by auditing the code. It's the only private messenger that uses open source, peer-reviewed cryptographic protocols to keep your messages safe.
Pro Supports encrypted group chats
Pro Has a desktop app
Signal Desktop can be used on multiple devices and has most features of the Android version, although it still requires you to register with your phone.
Pro Supports sharing of various different media types
Signal supports: emoji, pictures, videos, audio, contacts, any location and GIF.
Pro Note to Self feature
Allows you to "send: messages to yourself and sync to desktop so you can use Signal as a kind of encrypted Pushbullet alternative
Pro You can easily view all media exchanged
You can easily view all media shared in the chat without scrolling back to when it was shared.
Pro Annonymous Sender (Encrypted)
The sender credentials can be encrypted with the rest of the message, leaving only the recipient address readable by the Signal server. Even if Signal wanted they couldn't see who is talking with who by this mean.
Pro Works everywhere in every country
Unlike most messenger apps, Signal works reliably in all countries by securely circumventing internet censorship.
Pro Recommended by Edward Snowden
Edward Snowden uses this messenger and recommends it to everyone who is concerned about his privacy.
Pro User friendly
Discord follows the same type of interface design popularised by Slack, which is extremely clean and attractive, and doesn't clutter the interface with unnecessary chrome and cruft.
Pro Free for unlimited users
Unlimited amount of users.
Pro Can be used in browser
Users can invite others to join a Discord channel via a web link, which means no installation is required to use the software - which is one of the big typical barriers to entry for social software.
Pro Good 1-click invite system
Discord allows inviting people to a specific channel with a link. Links can be set to expire. Low effort/passive invite mechanics.
Pro Easy setup
You can quickly send invites to people and they can join in using the web client without having to create an account or install the app.
Pro Has low-latency VoIP support
Pro Supports video and text communication
Behaves and looks like Slack for regular text channels, but with the ability to create voice channels as well
Pro Numerous controls for setting member roles.
Deny access, Deny write message, Allow read messages etc.
Pro Ability to create bots
Discord provides an API for creating custom bots.
Pro Open source bots and management tools
Discord has a wide variety of bots for things from airhorn noises to automated server management, to leveling systems for chat. The bot API is open and there are dedicated sites for finding bots.
Pro Game integration
Discord shows which game each user is currently playing, which among other things helps users to form PUGs with minimal hassle.
Pro Dark theme out of the box
Pro Familiar for Slack users
For those that are used to the way Slack (a similar chat client) works, Discord will be familiar in its use, which lowers the learning curve quite a bit for those that have switched or tried Slack before.
Pro Low effort invite mechanics
Pro Android app has push notifications
Pro Syntax highlighting and Markdown support
The support is limited but still exists. It's a killer feature for dev teams.
Pro DDoS mitigation
Discord prevents users from being DDoSed out of games.
Pro Targeting of roles
Targeting roles allows for quickly requesting someone from a group e.g. artist, moderator, etc.
Pro Ability to thread channels
Ability to create channel categories for channels to sit inside of.
Pro Friendly payment policy
Free account have no tangible restrictions.
Premium account is just a way to say "thank you" to developers. And it work for all servers of discord (not as in slack). And it can be purchased by one who wants. In contrast to Slask, where all active members of the server should be "premium".
Pro Language localization
Have localization for many language, including Russian.
Pro Does not allow NSFW related things to be posted unless in a NSFW channel
Cons
Con Needs access to your phone number and contacts to work
Con Single device
Signal can only be registered to one mobile device at a time. But you can link Signal to Signal Desktop.
Con Servers hosted in the US
A security risk due to National Security letters, which require giving up data to the US state, and making it illegal to disclose that.
Con Unreliable notifications
Sometimes messages won't be received if the Signal app has been closed for a long time or hasn't been opened after booting the device.
Con Proprietary software
Discord is closed-source, meaning their code isn't available for inspection or reproduction
Con Based on Electron = eats a lot of ram
Con Some functions cut out and available only with "Nitro" subscription
Con Developer's previous company was sued for privacy violations, among other things
See:
http://classactionlawsuitsinthenews.com/class-action-lawsuit-complaints/openfeint-green-international-privacy-class-action-lawsuit-complaint/
https://www.ftc.gov/enforcement/cases-proceedings/closing-letters/openfeint-inc
Discord's privacy policy also states that while they might not sell your data, a company they get sold to will quite possibly attain said data and thus may be in "more" shady hands.
Con No self-hosting avaliable
Discord is wholly hosted by Discord (the company), you cannot run private instances, and all servers are hosted on their infrastructure. For most people, this won't really impact their usage.
Con Not a generic "team chat" tool
All the UI and the features are aimed specifically at communicating with your gaming team/clan.