While awaiting the official images, here is a look at some of the highlights for Debian 11:

- More than 59k packages are available in the Debian archive, with this release there being some 11k+ new packages.

- The Linux 5.10 LTS kernel is powering Debian 11 compared to Linux 4.19.

- Support for the exFAT file-system thanks to the new kernel support.

- Control groups v2 support.

- Use of yescrypt password hashing by default.

- There are many other updates too including GCC 10.2 as the default compiler (previously was GCC 8.3), LLVM Clang 11.0 rather than Clang 7.0, and many other updates.

- The "open" command is now an alias to xdg-open.

- LibreOffice 7.0 is available on the desktop.

- Driverless printing to USB devices via IPP-USB.

New in Ubuntu 18.04 LTS Bionic Beaver
Here are the highlights from the Ubuntu team on the new release:

Linux 4.15 kernel with Spectre and Meltdown patches and AMD Secure Memory Encryption support
Configure networking through netplan.io. ifupdown has been depreciated
Updated MD driver for software RAID improvements and new ZFS on Linux support
Python 2 is no longer installed by default. Python 2 will be moving from main in 20.04 LTS.
Supported by Canonical until 2023
Runs on all major architectures – x86, x86-64, ARM v7, ARM64, POWER8 and IBM s390x (LinuxONE)
New ubuntu-minimal images that are smaller and boot faster
A new, default server installer ISO with a new interface and faster install
LXD 3.0 – Linux containers including clustering, Qos, and resource controls (CPU, memory, block I/O/ graphics, and storage quota)
Updates to LXD (v3.0), DPDK (v17.11.1), Postgresql (v10.3), Libvirt (v4.0), Open vSwitch (v2.9), NGINX (v1.13), Qemu (v2.11.1), Docker (v17.03), Puppet (v4.10), MySQL (v5.7), PHP (v7.2), and more
OpenStack updated to OpenStack Queens release.
Here are a ton of other changes. You can check them out here.