Difference in Project deployment model and package deployment model in SSIS

When Using the Project Deployment Model	When Using the Package Deployment Model
A project is the unit of deployment.	A package is the unit of deployment.
Parameters are used to assign values to package properties.	Configurations are used to assign values to package properties.
A project, containing packages and parameters, is built to a project deployment file (.ispac extension).	Packages (.dtsx extension) and configurations  (.dtsConfig extension) are saved individually to the file system.
A project, containing packages and parameters, is deployed to the SSISDB catalog on an instance of SQL Server.	Packages and configurations are copied to the file system on another computer. Packages can also be saved  to the MSDB database on an instance of SQL Server.
CLR integration is required on the database engine.	CLR integration is not required on the database engine.
Environment-specific parameter values are stored in environment variables.	Environment-specific configuration values are stored in configuration files.
Projects and packages in the catalog can be validated on the server before execution. You can use SQL Server Management Studio, stored procedures, or managed code to perform the validation.	Packages are validated just before execution. You can also validate a package with dtExec or managed code.
Packages are executed by starting an execution on the database engine. A project identifier, explicit parameter values (optional), and environment references (optional) are assigned to an execution before it is started. You can also execute packages using dtExec.	Packages are executed using the dtExec and DTExecUI  execution utilities. Applicable configurations are identified by command-prompt arguments (optional).
During execution, events that are produced by the package are captured automatically and saved to the catalog. You can query these events with Transact-SQL views.	During execution, events that are produced by a package are not captured automatically. A log provider must be added to the package to capture events.
Packages are run in a separate Windows process.	Packages are run in a separate Windows process.
SQL Server Agent is used to schedule package execution.	SQL Server Agent is used to schedule package execution.