For the complete novice entering this field, I have to give you fair warning: you may encounter snobbery, eye rolling, corrections and other forms condescending behavior when you speak of “3D Printing” to an engineer or manufacturing expert. The wide range of manufacturing processes that have been summarily lumped together under the general knowledge term “3D Printing” has a long history of trade names and industry terms that have fallen in and out of use.
“3D Printing” was originally the trade name of a single process developed at MIT and licensed to Zcorp around 1990. It involved injecting a glue-binder through successive layers of plaster powder. The bind liquid could be colored for fully “3 Dimensional Prints”. Through most of the following decade, there were a range of technologies that produced accurate, but relatively weak plastic, paper or plaster parts. Since these were great for trying out designs, but not suitable for production parts, they were grouped together under “Rapid Prototyping”. The most common of these were produced via Stereolithography (commonly referred to as SLA), which led to parts being referred to as “SLA Parts”, even those that were not necessarily made by that specific process.
As the processes matured in the first decade of the 21st century, and metal, ceramic and plastic parts were being used directly in commercial products, the term “additive manufacturing” came to replace “rapid prototyping” in industry. Meanwhile, the Rep Rap project and its offspring, Maker Bot popularized fused filament-based production with their low-cost systems for the general public. These brightly colored, somewhat rough parts were called “3D Printed” in popular literature. Today, 3D Printing can refer to either these amateur polymer systems or be used to refer to all additive manufacturing processes in general media.
So, when you want to refer to all processes that produce 3D parts via the stacking of layers applied via a digitally controlled system, check your audience. If you’re at risk of eye-rolling, use “additive manufacturing”, if you’re at risk of blank looks, use “3D printing”.