Welcome @jiyeke!
@vnadkarni has answered your question well, I would just add a couple more things.
There’s no such thing as Confluent Kafka. Confluent includes Kafka within its distribution, but as @vnadkarni said, Kafka owned by the ASF and so it is only ever Apache Kafka.
Confluent have built ecosystem component around Apache Kafka, including:
- ksqlDB (streaming database)
- Schema Registry
- REST Proxy
- Web-based GUI
- Clients for Python, Go, C/C++, .NET
- Many connectors for Kafka Connect
You can get these on-premises (Confluent Platform) or in the Cloud (Confluent Cloud).