Power apps is a PaaS (Platform as a Service) that enables developers to create apps that run on various platforms.
There are 2 types of power apps.
1. Model Driven App
2. Canvas App
Here are some spotted differences between these two types of apps.
Model driven apps are
1. Data driven.
2. Connects to one data source at a time i.e. Data verse
3. CRM customizations can be included
Canvas apps are
1. UI driven
2. Connects to multiple data sources at a time
3. Excel styles formulas and conditional check based implementation