The free Wolfram Engine implements the Wolfram Language with interfaces
suitable for use in software projects. The Wolfram Engine is the heart
of Wolfram products such as Mathematica, Wolfram|One and Wolfram|Alpha.
It is licensed for non-production use.

The Wolfram Engine and Mathematica are the same core engine, but with a
different interface and different licensing.

The Wolfram Engine contains a program WolframScript for running the
Wolfram Engine from a command line or script.