Rust: What is the difference between Stream and Sink?

1use futures::stream::{self, StreamExt};
2use futures::sink::SinkExt;
3
4// Stream: produce
5let mut stream = stream::iter(vec![1, 2, 3]);
6while let Some(val) = stream.next().await {
7    println!("{}", val);
8}
9
10// Sink: consume
11let (tx, mut rx) = tokio::sync::mpsc::channel(32);
12tx.send("hello").await.unwrap();