= Solution
Both terms concern \b[time-dependent <strain> under <stress>]. Here <radiation-enhanced creep> means irradiation accelerating a mechanism that also operates thermally, whereas <radiation-induced creep> emphasises deformation driven by irradiation-specific defect fluxes. The literature sometimes uses <irradiation creep> as an umbrella, so identifying the mechanism is more informative than treating the names as mutually exclusive experimental categories.
<radiation-enhanced diffusion> maintains mobile point-defect concentrations above their thermal equilibrium values. Under a load, this can accelerate diffusion-mediated deformation or <dislocation climb> and thereby enhance a <creep (deformation)> mechanism. The effect depends on <temperature>, defect production, recombination and sinks; simply raising the specimen <temperature> by radiation heating is a different explanation and must be controlled.
<radiation-induced creep> can remain important where unirradiated <creep (deformation)> is small. <stress-induced preferential absorption> gives differently oriented <dislocations> unequal capture of irradiation-produced defects, producing directional climb. Climb can also enable further glide by relieving obstacles. A schematic low-stress relation is
$$
\frac{d\varepsilon_{\rm irr}}{dD}\simeq B_{\rm irr}\sigma,
\qquad
\dot\varepsilon_{\rm irr}\simeq B_{\rm irr}\sigma\dot D,
$$
with a condition-dependent compliance $B_{\rm irr}$, not a universal constitutive law. Coupling to <void swelling> and evolving sinks can add further terms.
Compare stressed and unstressed specimens in and out of irradiation at matched actual <temperature>, and resolve longitudinal, transverse and volumetric <strains>. Unstressed <irradiation growth> or <void swelling> is not itself evidence of <creep (deformation)>, and stress-enhanced <void swelling> must not be included automatically in a fitted <creep (deformation)> <strain>. These controls distinguish a mechanical response to irradiation defects from ordinary <creep (deformation)> or a different dimensional-change mechanism.
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