Types of Processes in Microsoft Dynamics 365
When creating a Process from the Settings -> Processes area you have 4 options:
Action - An Action is a set of steps configured by a CRM Administrator and then called through code (such as a plugin). This allows you to have an Administrator control the business logic but the developer could determine when that logic is used
This is something to consider when you have limited access to a developer so you can minimize your dependence on them
For example - You could have a Plugin firing when a task is added to a queue and it calls an Action to assign it to the manager. The Plugin could determine when it needs to fire, but the Action could control how the manager was set.
Business Process Flow - Business Process Flows allow you to create the ribbon across the top of a record that helps walk a user through a process
The most common example is the sales process where a salesperson is guided through the Lead to Opportunity to Account process and encouraged to enter all the appropriate data along the way
This can span multiple entities and include conditional branching logic based on input data
Workflows - Workflows are automated processes that fire behind the scenes
These can fire automatically or be manually triggered by a user (on demand)
Workflows do not allow for any user interaction in the process. It will not pop up and ask the user for more information to direct the process. It can wait on a specific action to occur.
These can fire in the background (asynchronous) or in real time (synchronous)
Dialog - a Dialog is basically a wizard that will walk the user through a series of questions and then acts on the entered data
Manually triggered on only one record at a time
Relies on manual intervention
Deprecated in v9 so don't get too attached
Business Rules are similar to processes in that they allow more complex logic to be achieved without code. These are configured within the entity or form that you want to work on. Business Rules ask for a condition and then allow actions based on that condition. The actions can be show/hiding a field, setting the value of a field, setting a field to required, etc. In 8.2 a "Recommendation" option was also added which allows you to suggest an action for a user and they can choose whether to implement or not.
Hopefully this gives you a high-level overview of the types of automation you can implement in Microsoft Dynamics 365.