LEDs are used to grow many varieties of coral, with a lot of success. The article below talks about many of the factors you have to consider when emulating sunlight.
Depends on what you mean by comparable. LEDs (and CFLs) aren't blackbody radiators. It's possible with many fine tuned LEDs you can get a spectral power distribution approximate to that of the sun, but... for now it's expensive. And difficult to make consistent.
https://orphek.com/led-light-chose-aquarium/