Apparently, the big difference will be that this new service won't require a Google account, which must be a nagging issue for consumers in emerging markets for some reason or another I frankly do not understand. The hope is that by removing this sizeable (???) barrier to usage, people will start using this not-Hangouts service, which will be free, instead of WhatsApp or Line or one of another half-dozen or so popular mobile messaging services their friends already use which is why they use it and not, say, some random service made by Google.