Rust releases are just compiler toolchain, maybe some new syntax features. Java includes the JVM which is subject to way more security issues and needs much more frequent updating.
There are some actual removal of feature too (breaking backwards compatibility on purpose). But those come with deprecation warnings for years before the actual feature is removed. And even then quite often it is still possible to enable with some feature flag for a version or two.
Patches are released continuously. The upstream versions get them immediately and they are then backported to LTS versions. Whether the patches actually become available simultaneously I cannot say without.