pip vs Spack

pip installs Python packages from PyPI and other package indexes, as well as from version control URLs, local project directories, and source archives. It supports source distributions and wheels, resolves dependencies, and can install an environment specified in a requirements file. Its install command can produce a JSON report of installed packages. pip runs on Linux, macOS, and Windows, and the current version supports CPython 3.10 through 3.15 and the latest PyPy3. Other operating systems and Python versions are not supported by its maintainers. It is commonly included in virtual environments and Python downloads from python.org; ensurepip and get-pip.py are also installation options. An experimental standalone zip application is available, but its documentation advises against production use. pip is free. It does not collect telemetry, though it sends non-identifying details such as Python version and operating system to the remote indexes it accesses. Remote tampering checks are not enabled by default; hash-checking mode and binary-only installs are listed as more secure options.

Spack is a package manager for installing scientific software on supercomputers, Linux, macOS, and Windows. It is designed for large supercomputing centers that share software across clusters and varied architectures, and is available at free. Users can choose package versions, compiler choices, target architectures, and compile-time options, while controlling direct and transitive dependencies. Spack can build stacks that combine Python or R packages with C, C++, or Fortran libraries. Each distinct package and dependency configuration receives its own prefix, so different builds can coexist without a new installation disrupting an existing one. Software can be installed to a user-selected directory without administrator privileges. Spack primarily builds customized software from source and also supports binary installation through build caches. It supports lockfiles, environment management, and private registries. Package recipes are Python scripts, and the `spack create` command generates starter boilerplate. The project is distributed under either the MIT license or Apache License 2.0, at the user's option.