What is TAR?

A tape archive, and it does exactly what the name suggests: bundles files together in order without compressing anything. On its own it saves no space. It's the first half of nearly every Unix archive, and what build pipelines and Docker expect to be handed.

What is ZIP?

The archive format both Windows and macOS open by double-clicking, which is most of why it won. Each file inside is compressed on its own, so you can pull one out without unpacking the rest - handy for browsing, slightly worse for compression ratio.