The question as asked cannot receive a definitive answer, because how luminous a light source appears depends on the response curve ("luminosity function") of the receiver. Normal human eyes do not produce a visual sensation for infrared and ultraviolet, so what the response curve should be depends on the decision by the author.
Graph of photopic luminosity function of the human eye (black) including CIE 1931 (solid), Judd-Vos modified (dashed), and Sharpe, Stockman, Jagla & Jägle 2005 (dotted); and scotopic luminosity function, CIE 1951 (green). Image by Dicklyon and Innesw, available on Wikimedia under the Creative Commons CC0 1.0 Universal Public Domain Dedication license.
Note: This is why we have special photometric units of measurement such as candela, lumen and lux and we don't measure light in radiometric units. For example, one candela is 1/683 watt per steradian at 555 nm, but at 690 nm (deep red, near infrared), one candela requires almost one watt per steradian.
Nevertheless, some general impressions can be provided based on the vast number of infrared (and, since digital photography, ultraviolet) photographs available since the beginning of photography. (It is actually hard to make a photographic sensor with the exact same response curve as the human eye...)
Backyard garden near Moscow. Infrared photograph by sovraskin, available on Flickr under the CC BY 2.0 license.
Look at the (pretty typical) infrared photograph of a backyard near Moscow. Note the major dissimilarities with a photograph in the visible spectrum:
Grass and foliage appears very light; this is because leaves reflect as much infrared light as plant physiology can achieve -- infrared light carries heat, and plants don't have a good way of cooling, so they try to avoid absorbing infrared.
The cloud in the sky have a dramatic contrast. Clouds reflect infrared light, so they appear light, whereas clear sky is mostly devoid of infrared, so it appears dark.
Bobcat at night. Infrared photograph captured by a remote camera trap operated by the [American] National Park Service. Photograph in public domain, available on Flickr.
- When taking infrared photographs at night, mammals and birds appear light (sometimes even as light sources), because they are warmer than the environment.
Flowers appear dramatically different in ultraviolet; bees and other pollinating insects see ultraviolet light, and flowers are optimized to be attracted to insects and not so much to humans. There is an excellent blog, Vis-UV-IR Flower Photos by Dave Kennard, with many photographs of flowers taken once in visible light, once in ultraviolet and once in infrared, with descriptions of the differences. You may also want to read "Ultraviolet Patterns in Flowers,or Flowers as Viewed by Insects.
Images of a Mimulus flower in visible light (left) and ultraviolet light (right) showing a dark nectar guide that is visible to bees but not to humans. Photograph by Plantsurfer, available on Wikimedia under the CC BY-SA 2.0 UK: England & Wales license.