Which is better, niacinamide or vitamin C ampoules?

I bought a vitamin essence that is said to be good for whitening, but when I looked at the ingredients list on the back, I noticed that the niacinamide content was higher than that of vitamins. I've been looking into it with interest because both niacinamide and vitamin C are known to be good for whitening and improving blemishes. To be honest, I don't currently have severe blemishes or hyperpigmentation, but I plan to use it consistently to prevent future pigmentation.

I am curious about the differences in effectiveness between niacinamide and vitamin C ampoules, and I would also like to know if it is okay to use both together. When looking at reviews, it seems there are more reports of side effects like skin irritation or stinging with vitamin C, so I am wondering if niacinamide can also cause irritation depending on skin type.

Between the two, I really want to use the less irritating product, but I am also concerned that choosing mild ingredients might reduce the effectiveness of whitening or blemish improvement. I would like to know which ingredients are helpful for preventive care while allowing for consistent use without burdening the skin.