Infill 3D model refers to a 3D print’s internal support structure (affecting strength, weight, and material use), while ABS 3D model denotes a model printed with ABS plastic (a tough, heat-resistant material)—they differ as a structural element vs. a material type.
Infill controls how solid a print’s interior is (e.g., 10% infill saves plastic for non-load-bearing parts; 50% balances strength and weight). ABS is used for durable, impact-resistant parts like toys or mechanical components.
If you need to adjust durability without changing material, tweak infill; if you need temperature or impact resistance, choose an ABS model.