You can use it casually. Usually different packaging is enough. No special requirements. If you take the formalization route, you should pay more attention to the brand. The series of products are now also starting to apply for trademarks. This can be learned from the practices of large companies. Such as: L'Oreal Paris Snow Series.

Experts from Beijing ***Teng Intellectual Property Agency Co., Ltd. suggest: Similar situations include the Apple IPAD series, etc. Big brands will also register series of products that have already registered trademarks.