Warning: This is based on GNU Plotutils, which is venerable but unmaintained software last updated decades ago.
Guile Plotutils has two main components: plot and graph.
The plot component expresses GNU Plotutils’s plotting library, which basically does vector graphics onto image surfaces. You might compare it to SVG or the Cairo library.
The graph component expresses GNU Plotutils’s graphing capabilities, which can plot data or functions on a set of xy axes.