Vue and Bryce seem to use different approaches to the behaviour of textures with respect to light. Bryce has diffuse and ambient settings, Vue has diffuse, ambient and luminescent. Luminescent seems to be what is ambient in Bryce. If you import your Poser model all textures are set to 60% diffuse and 40% ambient and changing these settings is either extremely tedious or I never found the quick way to do it. Note: the Vue 4 demo has no bitmap texture bump mapping, but I'm told this is present in the full version.