REST-WS module exposes the features and services of Platform 2.0 via rest endpoints. Until Platform 1.10, almost all platform features were accessible via the REST-WS module. But since then, we have not tracked what features from OpenMRS TRUNK (i.e Platform 2.0) are missing from the REST-WS module.
The task is to identify and report 3 such features.
You might want to look at the git commit logs of both projects besides installing and manual testing.
Another way to find the features missing in webservices.rest module is by studying database changes described here :