What is the purpose of each folder (module) in the Package Directory in sfdx-falcon project?

Question

I am working on an sfdx project based on the sfdx-falcon template. I studied all available materials that I could find:

1. SFDX-Falcon Project Template
2. Salesforce DX 201 - Advanced Implementation for ISVs
3. Two SFDX project folder structure questions

Generally it's clear how to work with a falcon project. However, when it comes to details, I am confused with the purpose of certain folders (modules), or where to put some components (e.g. pages, applications, flexipages etc.) To my bitter disappointment I couldn't find reasonable explanation so far.

Question 1

For example, in DX Custom Metadata Types are stored in the customMetadata folder, and it is confusing when I see customMetadata and customMetadataTypes folders in the Schema folder. So what purpose does each of these two folders serve in the Schema folder?

Question 2

I have a custom application (.app-meta.xml) in the applications folder. Where should I put my apps: somewhere in the main module or create a feature module for this?

Answer 1

Answer 1 CustomMetadataTypes and CustomMetadata are 2 different metadata representation that is why they are stored in 2 different directory. CustomMetadataTypes can be considered as a custom metadata shape like sObjects being shape of your records. However CustomMetadata is the input for that shape.

In other words CustomMetadataTypes are special object types and CustomMetadata is a special type of record.

Answer 2 That depends on how you manage your metadata structure if your application contains only a specific feature related items and no dependency to any other metadata apart from your default and the subjected feature then you can store the app in your feature directory.