There are lots of FAQs on the Mencap website, including 'what is residential care?' and 'what is supported living?'. Take a look here
The main difference is that in a supported living setting, a person will have their own tenancy agreement and support can range from visiting to 24-hours, depending on need. Residential care combines care and accommodation, with 24 hour support. The person lives under the home's care, rather than having their own tenancy agreement.
I've had a quick google elsewhere too, have a look at the following links which might be helpful:
I hope that helps!