| Boron nitride nanotubes (BNNT) | Carbon nanotubes (CNT) | |
| Electrical | Insulating (~5.7 eV wide-bandgap semiconductor) |
Metallic or semiconducting |
| Optical | Strong UV absorbers and transparent in the visible; visible emitters | Ultraviolet, visible, and near-infrared absorbers; semiconductors are near-infrared emitters |
| Radio Frequency transparency | Yes (e.g. for 5G or radar) | No |
| Thermal stability | Stable to at least 800°C in air | Up to 480°C |
| Thermal neutron capture cross section | Boron isotope enrichment dependent (10B ~3825 barns vs. 11B ~0.0055 barns; N = 1.9 barns) | C = 0.0035 barn |
| Bond polarity | Polar (B-N) | Nonpolar (C-C) |
| Piezoelectric behavior | Yes (0.25 – 0.4 C/m2) | Yes |
| Surface morphology | Corrugated | Smooth |
| Color | White or translucent | Black |
| Toxicity | Very low, possibly no cytotoxicity | Yes |
| Theoretical thermal conductivity (vs. copper ~400 W/m∙K) |
~3,500 W/m∙K (axial) | |
| Mechanical strength (Young's modulus) |
~1.2 TPa | |
| Coefficient of thermal expansion (CTE) | -1 x 10-6 | |