I am wondering what the differences between perspective (1 point/2 point/3 point) and the term foreshortening is when drawing?
Perspective is the mathematical rule which defines how a 3D scene is mapped to 2D image. 1,2 and 3 point perspectives are construction shortcuts how to draw rectangular shapes and other parallel line structures.
Foreshortening is the visible effect to shapes when they are drawn to have an impression of proper perspective. An artist does not make exact mathematical perspective constructions for every detail during the drawing because life is too short for it. Foreshortening is based on talent, experience and a set of learned thumb rules how to draw this and that from different directions and distances. It must come out nearly automatically to be productive.
The skill is developed by exploring existing images, dummy models and making thousands of experimental drawings - at first only few objects with little details and fuzzy lines, then bigger compositions and richer & sharper details.
There are plenty of tutorials how to start to develop the needed skills.