Replica Sets vs Sharded Clusters in MongoDB:

In Simple Words:

• Replica Sets: High availability (1 Primary + multiple Secondaries with automated failover).
• Sharded Clusters: Horizontal scaling by distributing data across shards via a shard key.

// Enable sharding on collection using a hashed shard key:
sh.enableSharding("production");
sh.shardCollection("production.users", { "_id": "hashed" });