What is the difference between social.plus and Stream?

Both are infrastructure you build into your own app. Stream offers chat, video and audio, activity feeds and moderation as separate products, each with its own SDK and pricing. social.plus brings social engagement features together in one integrated layer: feeds, groups and forums, stories, clips, live streaming, chat and moderation, with SDKs, UIKit components and APIs across all of them. social.plus also includes operational tools that sit above the SDK layer: the Console for moderation and content management, and the Dashboard for engagement analytics.