The arbutin that we usually talk about usually refers to α-arbutin; it is a natural active substance extracted from a variety of different plants through microbial transformation and enzymatic synthesis.
Specifically, α-arbutin 99% CAS No. 84380-01-8 inhibits the formation of melanin by inhibiting the activity of tyrosinase. Niacinamide, on the other hand, blocks the transfer signal of melanin to keratinocytes, promotes cell metabolism, avoids melanin precipitation, and promotes the metabolic process of melanocytes.
Niacinamide for skin:
First of all, if niacinamide is added to skin care products, it can almost default to repairing the skin barrier and improving the skin's ability to protect against external aggressions. Secondly, if the concentration of niacinamide reaches 2%, it can brighten the skin tone very well, and if the concentration of niacinamide reaches 5%, it has the effect of lightening fine lines and delaying skin aging.
Because the whitening principles of the two are different, the effect is also different for people with different skin types and physiques; you can make a choice based on your own skin type and actual experience of using the effect.