Though both can act as a primer, concealer, foundation, moisturiser, and sunscreen, they have different levels of coverage. Especially, with covering skin imperfections, so it mainly depends on your skin's needs. BB cream is mostly useful on days when you only need sheer coverage, great for "no makeup" makeup looks. They can lightly conceal minor blemishes. Meanwhile, CC creams offer more coverage. They mostly serve as tools for colour control or complexion correction. They're specifically made to cover redness, dark undereye circles, uneven skin tone, hyperpigmentation and even acne scarring. However, CC creams often have lighter consistency, so if you're looking for one that can last a day, BB creams might be a wiser choice.