This paper presents an extensive comparison of the mechanical properties and failure mechanisms of a recently developed thermoplastic (Elium ®) 3D fabric-reinforced composite (3D-FRC) with the conventional thermoset (epoxy) 3D-FRC. Experiments involved tensile tests, compression tests, V-notch shear tests, and short beam shear tests for specimens produced through the vacuum-assisted resin infusion process in each case. These tests were used for the determination of in-plane elastic constants, failure strengths and for investigating the failure mechanisms. A micro-mechanical model validated against these experiments was used to predict the remaining orthotropic elastic constants. This work enhances our understanding of the mechanics of infusible thermoplastic 3D-FRC as a new class of emerging materials and provides useful data which substantiates that this unconventional thermoplastic resin is also easier to recycle, uses similar manufacturing processes and can be a suitable replacement for conventional thermoset resins. © 2021, The Author(s), under exclusive licence to Springer Nature B.V.