What is different about the processes?
FDM builds a part by depositing heated thermoplastic filament. Resin processes such as SLA cure liquid photopolymer with light. Their support, surface and post-processing requirements differ. The exact machine, material grade, geometry and production setup still matter when judging an individual part.
Manufacturer comparisons are useful process references, not proof of the material inventory or capability of a particular printing service. Ask the quote to state the process and grade proposed for your file.
Compare the requirement, not a generic winner
| Requirement | FDM discussion | Resin discussion |
|---|---|---|
| Visible detail | Which small features and layer surfaces matter? | Which fine features, surfaces and support-contact areas matter? |
| Fit and assembly | How should orientation and mating interfaces be checked? | How should supports, post-processing and mating features be checked? |
| Handling | Which material grade and layer orientation suit the intended use? | Which resin grade and post-cure condition suit the intended use? |
| Finish | Which faces can show process marks and which need finishing? | Where may support contacts remain and what appearance is required? |
| Environment | What load, temperature or exposure must be evaluated? | What load, temperature or exposure must be evaluated? |
Split a mixed brief into two decisions
Define properties for the actual grade
Manufacturer datasheets describe particular products under specified test conditions. A generic family label such as PLA, PETG or “tough resin” is not a complete specification. Identify the selected grade and the conditions relevant to the finished part; avoid reading a catalogue value as a universal result for every orientation or geometry.
If the job depends on a dimension or fit, mark it in the drawing and define what will be checked. A small layer height is not, by itself, a promise about overall dimensional accuracy. For a fit prototype, state which real mating part or drawing will be used in the review.
Include post-processing in the comparison
Specify the appearance you want to receive, not just the process that makes the initial shape. Ask what support removal, cleaning, curing, surface work and assembly are included where relevant. A display surface and a hidden bracket may justify different finishing effort.
See how to specify a display finish and the material and process enquiry table. Bring the same requirements to the FDM service and resin service so any comparison is like for like.
Sources and further reading
Primary references checked on 21 September 2026. These explain the relevant concepts; they do not establish our current inventory or a quoted capability.