Element (formerly Riot), Discord, and Slack are all irc successors; Signal, Whatsapp, and Snapchat are sms/mms successors.
The differences used to be desktop vs mobile, primarily [semi]public group/community chats vs primarily private 1:1, and realtime with presence vs async. As technology has advanced, the differences have shrunk. I'd say the last real remaining difference is that the irc successors have named channels with granular permissions and static invite links, while the texting apps might have a group owner but otherwise give everyone full permissions, and people are usually added directly to the group (not invited).
In short: the texting replacements are geared towards communication with friends (ie, based on who you're talking to), while the irc replacements are geared towards communication, possibly with strangers, based on what you're talking about.