Which functionality is provided by Vagrant as well as by Docker?

Both Vagrant and Docker can share directories from the host file system to a guest. This allows the guest to access files and folders from the host without copying them. Vagrant uses the config.vm.synced_folder option in the Vagrantfile to specify the shared folders1. Docker uses the -v or --volume flag in the docker run command to mount a host directory as a data volume in the container2.

Both Vagrant and Docker can download required base images. Base images are the starting point for creating a guest environment. Vagrant uses the config.vm.box option in the Vagrantfile to specify the base image to use1. Docker uses the FROM instruction in the Dockerfile to specify the base image to use2. Both Vagrant and Docker can download base images from public repositories or local sources.

Both Vagrant and Docker can apply changes to a base image. Changes are modifications or additions to the base image that customize the guest environment. Vagrant uses provisioners to run scripts or commands on the guest after it is booted1. Docker uses instructions in the Dockerfile to execute commands on the baseimage and create a new image2. Both Vagrant and Docker can save the changes to a new image or discard them after the guest is destroyed.

Vagrant and Docker differ in how they start system images. Vagrant starts system images as virtual machines by default, using a provider such as VirtualBox, VMware, or Hyper-V1. Docker starts system images as containers by default, using the native containerization functionality on macOS, Linux, and Windows2. Containers are generally more lightweight and faster than virtual machines, but less secure and flexible. References: 1: Vagrant vs. Docker | Vagrant | HashiCorp Developer 2: Vagrant vs Docker: Which Is Right for You? (Could Be Both) - Kinsta® Web Development Tools