  The proposed CMBPol mission will be able to detect the imprint of topological
defects on the cosmic microwave background (CMB) provided the contribution is
sufficiently strong. We quantify the detection threshold for cosmic strings and
for textures, and analyse the satellite's ability to distinguish between these
different types of defects. We also assess the level of danger of
misidentification of a defect signature as from the wrong defect type or as an
effect of primordial gravitational waves. A 0.002 fractional contribution of
cosmic strings to the CMB temperature spectrum at multipole ten, and similarly
a 0.001 fractional contribution of textures, can be detected and correctly
identified at the 3{\sigma} level. We also confirm that a tensor contribution
of r = 0.0018 can be detected at over 3{\sigma}, in agreement with the CMBpol
mission concept study. These results are supported by a model selection
analysis.
