Kernel-based Virtual Machine (KVM) is a powerful component of the x86 hardware virtualization extensions required for Intel VT and AMD-V. Virtualization technologies have been growing steadily in their capabilities and adoption. Linux kernel has included the KVM component in the mainstream since 2.6.20. It is a crucial part of using virtualization on Linux machines, and is frequently used with software similar to QEMU.
LXD is primarily a container management tool. It utilizes Linux Containers (LXC) under the hood for containers. More recently it has embraced QEMU/KVM to run virtual machines (VM).
Installing CentOS Linux in a virtual machine with VirtualBox is a straightforward exercise. The exception comes when configuring Guest Editions on the operating system. I find it easiest to use a group install with Yum, before “inserting” the disc for Guest Editions. Using the following two lines in the shell will ensure that the C compiler and kernel are available for installing Guest Editions.
sudo yum groups install 'Development Tools'
sudo yum install kernel-devel-yourLatestVersionFurther guidance is available in the user manual. https://www.virtualbox.org/manual/UserManual.html#externalkernelmodules
VirtualBox is a hypervisor for x86, Intel64 and AMD64 computers. It offers a plethora of features to support a vast number of use cases. The open-source nature along with its GNU license are attractive qualities for all users. Visit their official website at https://www.virtualbox.org/.