When designing the process flow of your process, you can add work to be carried out automatically in your process, that is, without the need for human intervention. This behavior is implemented through the Automatic Activity 

When designing the process flow of your process, you can add work to be carried out by the end user. This behavior is implemented through the Human Activity 

You can visit below documentation for more info:

https://success.outsystems.com/Documentation/11/Reference/OutSystems_Language/Processes/Process_Tools/Human_Activity

https://success.outsystems.com/Documentation/11/Reference/OutSystems_Language/Processes/Process_Tools/Automatic_Activity

Hi phong vu ,

Human Activity :

The Human Activity allows you to specify and assign a work to be carried out by the end users in your application. Once the process flow execution reaches a Human Activity the end user or end users are informed (in their Taskbox) of the work that has to be carried out. Then, one of them executes the activity and signals in the Taskbox that the activity has been done, and the Human Activity execution finishes. The process flow execution continues to the next process activity in the flow path.

A Human Activity can have input parameters, output parameters and callback actions.

Human Activity is not available in Service Modules because this activity requires user interface.

Automatic Activity :

When designing the process flow of your process, you can add work to be carried out automatically in your process, that is, without the need for human intervention. This behavior is implemented through the Automatic Activity process activity which you can drag onto your canvas from the Process Flow Toolbox.

An Automatic Activity can have output parameters and local variables.

Whenever you have side-effects, such as adding, changing, or deleting entity records in the database or in external systems, design them in an Automatic Activity.

thanks,

Ramesh

Hi @Phong Do '
You can take reference from these below links to understand the difference between the human activity and automatic activity in BPT.

Human activity 

Automatic activity

Hope it is helpful for you.
Thanks,

Rakhi