Both janusgraph-<version>.zip and janusgraph-full-<version>.zip are the same except that `janusgraph-full-<version>.zip` includes Cassandra and ElasticSearch which can be quickly started with a convenient tool `bin/janusgraph.sh`. This is the convenient way to test JanusGraph with mixed indices without the need to configure and run your own ElasticSearch and Cassandra. That said, in most cases I would recommend to run your own installation of storage and mixed index backends.
Both these releases have JanusGraph Server (Gremlin Server) included. Thus, in production you should prefer using janusgraph-<version>.zip with your own backend storages installation instead of using janusgraph-full-<version>.zip.