It's all about wavelengths! Plants require wavelengths within the visible spectrum, roughly between 400nm and 740nm. UVA falls just under the visible spectrum, but is highly beneficial for faster growth, higher nutrient levels, and resistant to fungal infections. (source)
So, what exactly is UV, UVA and UVB? All light is categorized by different wavelengths, which you can see charted above as the Electromagnetic Spectrum. Visible light for humans and most reptiles occurs between roughly 400 nanometers (nm.) and 780 nm. Anything above that is infrared (which only some animals, like cats for example, can see). Ultraviolet light occurs from roughly 100 nm. to 400 nm., with UV light further broken up into groups A, B, and C.
However, various plants react differently to the UV light with differing outcomes. Several studies have noted the effects of UV-B light on plants, and unfortunately, they are mostly negative, specifically at higher UVB levels.
A key note to understand is that LED vivarium lights are actually UV lights also, because they emit light that is within the UV spectrum (specifically UV-A).
Regular household LED bulbs can be used to grow plants in vivariums or in your house - but they aren't going to promote the fastest or most vigorous growth depending on lumens (light output) and color temperature (mix of blue-red wavelength). The blue spectrum plays a major role in plant growth and germination, a cool-white color temperature LED of 6000K containing higher amount of blues is preferred over warmwhite LED containing less blue but more red colors.
Other benefits of using LED lighting for reptile habitats: