What is the difference between stanchions, posts, trusses, and struts?

Stanchion – Literally means an upright element. Some industries call posts or bollards that have tied loads on them stanchions.

Post – Vertical load-bearing element. Larger or thicker versions tend to be called columns.

Truss – A beam or similar, roughly horizontal, element composed of a number of sub-elements. Think of a beam with most of the unneeded mass removed. Think of the support structures holding overhead freeway signs.

Strut – a load-bearing element that can act both in compression and tension along its axis or longest dimension.