Yes, the reason is the same. Selenium is a direct gap semiconductor with a band gap (if you are not familiar with any of these terms, make sure you look them up) of about 2eV, which is right in the middle of the range of visible light. In the dark, the conduction band is essentially unoccupied, but when light is incident on it, electrons get excited to the conduction band, providing the ability to conduct electricity.
There are some very basic concepts you need to learn first. I suggest you start with Ohm's Law and understand the concept of resistance. Then you can try to understand what conductors and insulators are.