Differences between Dynamics CRM Workflows and Dialogs and Plug-ins

Differences between Dynamics CRM Workflows and Dialogs
Workflows	Dialogs
Can be either started by a user or can be automated.	Must be started by a user.
Asynchronous processes, and no user input. background process.	Synchronous processes, require user input, a wizard-like interface will popup
Triggers are supported for workflows	Triggers are not supported for dialogs.

Differences between Workflows and Plug-ins
Plug-in	Workflow
Executes immediately before or after the core operation (synchronous).Can also be queued to execute after the core operation (asynchronous).	Queued to execute after the core operation (always asynchronous).
Synchronous plug-ins can increase the platform’s response time because they are part of the main platform processing. Asynchronous plug-ins have less impact on server response time because the code is run in a different process.	Less impact on server response time because the code is run in a different process.
To register a plug-in with the platform requires a System Admin or System Customizer security role and membership in the Deployment Administrator group.	Users can interactively create workflows in the Web application. However, to register a custom workflow activity, the deploying user must have the same security roles as those required for registering plug-ins.
A plug-in registered for synchronous or asynchronous execution is restricted to complete its execution within a 2 minute time limit.	Works well for either short or long processes.
Both online and offline are supported. Works when the Microsoft Dynamics CRM for Outlook client is offline	Workflows do not execute when offline.
Plug-ins execute to completion. Plug-ins must be written to be stateless where no in-memory data is persisted.	Workflows can be paused, postponed, canceled, and resumed through SDK calls or by the user through the Web application. The state of the workflow is automatically saved before it is paused or postponed.
Plug-ins can perform data operations on behalf of another system user.	Workflows cannot use impersonation.

Differences between Background(Asynronous) VS Run-time Workflow

Real Time Workflow: 1. An RTW triggered on a particular event (e.g. Create, Update, Assign and Delete) can also be configured to run on demand. This will still run immediately once triggered rather than being queued to run at later point of time as an asynchronous workflow would. 2. Unlike an async workflow, when a real time workflow runs it can do so in the context of the workflow owner, or can be configured based on user who made changes to record. 3. RTW do not contain any delay or wait activities step. 4. CRM users must have organizational permission on the following two security levels to create and activate a real time workflow: CRM provides an option to convert existing asynchronous workflows into real time workflows without the need to define any manual steps & vice-versa... Asynchronous Workflow: Asynchronous workflows do remain an important option for carrying out high volumes of processes which aren't time critical, for example creating activities or sending emails. In these examples the operation will take place without halting the user process.