If you're getting involved with starting to report social value/impact, and find yourself confused about all the different models, standards, bodies, and approaches, then don't panic - you're right where you should expect to be!
Preparing 'social accounts' is often likened to the preparation of a set of financial accounts - tracking what resources have been used, and what's changed (good or bad) at the end of a period.
However - as a species, we've been collectively agreeing how to 'do' financial accounts for about 8 millennia (the earliest reference I can find dates back to about 8,000BC in ancient Sumeria...). But we've only really been doing 'social' accounts for about 150 (the earliest references I'm aware of are co-operative societies in the mid nineteen century sharing how they were impacting on their members and communities).
So if we've been working on agreeing consistent standards and approaches for financial accounts for this long, why is there the sense of urgency and panic to nail the way in which we report the social value and impact alongside the financial stuff?
And just to add to the complication, financial accounting had only a few key audiences who were interested that it was gotten 'right' (investors, regulators, government), whereas social value and impact has far wider groups that it needs to satisfy (providers, commissioners, communities, employees, beneficiaries, customers, grant making bodies, policy makers, and so on and so on...)
So isn't it about time we stopped panicking that we've not yet reached a global consensus on the measures we should all be using when we talk about our value and impact..?
(Unless you're the Bank of England, who've just set a 2 year deadline on us all to figure them out before they make up and impose their own!)