Short and Sweet
All Microsoft Dynamics 365 CE (Customer Engagement/Customer Relationship Management) Applications are Power Platform Model-Driven Apps.
Microsoft Dynamics 365 Sales -> Power Platform Model Driven App built by Microsoft, Configured, Customized or even Extended by Microsoft Partners or Customers
Microsoft Dynamics 365 Customer Service -> Power Platform Model Driven App built by Microsoft, Configured, Customized or even Extended by Microsoft Partners or Customers
Microsoft Dynamics 365 Field Service -> Power Platform Model Driven App built by Microsoft, Configured, Customized or even Extended by Microsoft Partners or Customers
Microsoft Dynamics 365 Contact Center -> Power Platform Model Driven App built by Microsoft, Configured, Customized or even Extended by Microsoft Partners or Customers
Microsoft Dynamics 365 Project Operations -> Power Platform Model Driven App built by Microsoft, Configured, Customized or even Extended by Microsoft Partners or Customers
Microsoft Dynamics 365 Customer Insights/Journeys -> Power Platform Model Driven App built by Microsoft, Configured, Customized or even Extended by Microsoft Partners or Customers
Microsoft Dynamics 365 Marketing -> Power Platform Model Driven App built by Microsoft, Configured, Customized or even Extended by Microsoft Partners or Customers
ETC
but what about Power Apps/Canvas Apps?
We often create Microsoft Canvas Apps and embed them in Microsoft Model Driven Apps just like we embed Power BI Reports, Microsoft OneNote, Microsoft SharePoint and so much more.