Custom metadata types versus custom objects
Key Takeaway
Custom metadata type records are metadata and deploy with the app, while custom object records are data and stay behind.
A custom metadata type is an object that holds app configuration as metadata rather than business data. App builders use it to store things like region mappings, rates, or business rules, instead of hard-coding those values. A custom object is different because its records are data.
What a custom metadata type is
A field name like First Name is metadata, while a value like Amy is data. A custom metadata type is an object that defines the structure for application metadata. Its fields, field values, and records are all metadata, not data.