for instance, how come we’re told to wear sunscreen in broad natural day-light but not artificial light like indoors?
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Light is only a single type electromagnetic radiation. Specifically, what we call light refers to **visible** light.
There are many other types of electromagnetic radiation and they lie outside the visible light part of the electromagnetic spectrum. X-rays, gamma rays, radio waves, and so on.
A light bulb only emits radiation in the visible part of the spectrum (and a little bit of infrared, since most lights emit heat as well).
The Sun is a giant ball of gas that functions as a fusion reactor. The radiation it emits goes far beyond visible light. It emits ultraviolet, infrared, radio waves, X-rays and gamma rays.
Out of those, the radiation with longer wavelengths than visible light (infrared, radio, microwaves) are not generally harmful to us since they carry less energy.
The radiation with shorter wavelengths (ultraviolet, X-rays, gamma rays) is **dangerous**. The damage can range from a simple sunburn, to skin cancer.
Thankfully, the earth’s atmosphere filters out most of the nasty stuff. What you’re usually left with is ultraviolet. That’s what you use sunscreen for.
In short, you don’t have to worry about none of the harmful radiation that the Sun emits from a regular light bulb.
A (classical) house light is a simple tungsten filament heated until it becomes incandescent. Think of how metal glows when it’s red hot. At that temperature, it radiates light that falls within the visible spectrum, which is why you can see it.
On the other hand, the Sun being a fusion reactor, is millions of degrees hotter. At those temperatures, the naturally radiated energy falls in the higher, more dangerous electromagnetic bands such as X-rays and gamma rays.
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