Cybozu's kintone is a product specialized in database features.
It is a cloud-based workplace platform that lets you create various business applications for more efficient business operations.

Custom apps are the database feature of Cybozu Office.
This feature is available for Cybozu Office Premium license users.

• Cybozu Office
  Cybozu Office is a groupware product.
  In addition to the database feature, custom apps, the product comes standard with features such as scheduler, facility reservation, bulletin board, and file management, all of which are essential for sharing information across multiple departments and within a company.
  If you are looking for the groupware features, such as the schedule management feature and facility reservation feature for meeting rooms, in addition to the database feature, Cybozu Office fits your needs.
  Note that Cybozu Office is a groupware product designed for small and medium-sized companies. If you plan to have 100 users or more, consider purchasing Garoon instead.
  Garoon product website
  The following page explains the differences between Garoon and Cybozu Office.
  Differences Between Garoon and Cybozu Office
• kintone
  With kintone, you can build business applications tailored to your work, whether it is customer management, daily reporting, or any other tasks. You can apply plug-ins to extend existing features or use APIs to integrate the product with third-party solutions.
  In addition, kintone's Space feature lets you create dedicated spaces (bulletin boards) for specific topics. You can use this feature to centralize the communication necessary for moving forward projects and tasks.
  
  Note that kintone does not provide scheduler and facility reservation features.
  If you are looking for groupware features in addition to kintone, consider purchasing Cybozu's groupware products, such as Cybozu Office and Garoon, together with kintone.
  Garoon provides a connector for integrating with kintone. For details, refer to the following page.
  Using kintone and Garoon together

Both the custom apps of Cybozu Office and kintone let you create applications tailored to your work.
Based on the features needed for your work and your business operations, consider which product suits you best.
Refer to the following comparison chart for the main differences between the two.