Parylene and acrylic resins are both conformal coatings. Most of the similarities stop there. Because their properties vary so much, they have their own unique uses and capabilities.
Parylene Coating Blog by Diamond-MT
Depending on your application, choosing to use conformal coating equipment can be a very wise choice for maximum efficiency. I would recommend use of the conformal coating process decision worksheet to determine your coating needs and whether you should outsource conformal coating prior to purchasing a machine.
How to get Repeatable Conformal Coating Thickness
Measuring your conformal coating thickness is one thing, however making it a reliable and repeatable thickness is something else all together. There are three main ways of conformal coating application where a repeatable thickness can be obtained, however, a fair degree of training and skills are needed to achieve this.