Per https://github.com/pegasystems/pega-helm-charts/tree/master/charts/pega#tiers-of-a-pega-deployment

"stream (Deprecated)  For Pega Platform release 8.8 and later, Pega has deprecated the use of embedded "Stream tier" nodes.

For new deployments, Pega recommends that you enable an Externalized Kafka configuration under External Services; for existing deployments, nodes that run an embedded deployment of Kafka and are not exposed to the load balancer. Pega requires that these nodes use the node classification “Stream” nodetype."

Does this mean that "stream" node is deprecated, i.e. no longer needed, using the Externalized Kafka configuration?

If the answer is yes, then can someone explains the differences between "embedded deployment of Kafka" and "Externalized Kafka configuration"? 

I am asking this question because to my best knowledge (I could be wrong though), even in "Stream" node, Kafka is running in a separate process other than the application server (JBoss for example) in which Pega runs. 

So Kafka runs separately from Pega process, not run in the same JVM. 

In that case, what does "embedded deployment of Kafka" mean exactly? 

And further, what does the Pega process on "Stream" node do exactly, and why the "Steam" node can be eliminated once Kafka runs on another node?