Pulled latest versions of both images, Debian Bookworm and Ubuntu Noble Numbat. To my surprise, when I run the docker image ls, the Debian is about 117 MB vs the Ubuntu being 76 MB.
I used to believe, so far as Linux distributions go, Debian is more barebone, and Ubuntu builds on top of it. So what explains the difference in image size? As from a functional perspective (library compatibilities) they are almost equivalent, is it advisable to build from Ubuntu rather than from Debian?
The difference in image size is due to the specific packages and configurations included in each distribution’s base image. While Ubuntu is derived from Debian, its base image is optimized differently. Both are functionally similar, so if the smaller size of Ubuntu fits your needs, it is advisable to build from Ubuntu for efficiency.
Either people use a base image of a distribution they are found of, is required by the application that they want to containerize, or specifically aim for a base image for a small target image size.
Debian usually provides a -slim images, e.g. debian:bookworm-slim, which provides a similar small footprint as the ubuntu images.