Triggers and Workflow rules are the most important and powerful tools. Both having our own Pros and Cons. Below we have listed some of the points:

Triggers:

• A trigger is a very powerful control in Salesforce. If you want to do a lot of coding then it is best to use a Trigger that executes before or after when a record inserted, updated or deleted.
• You can access the Trigger beyond the object and related to that objects.
• You can execute 20 DML operations in one trigger.
• You can execute 20 SOQL’s from database in one trigger.
• A trigger can work across objects.
• Coding is required for the Triggers.
• Trigger executes on before and after some actions.

Workflow rules:

• Workflow Rules are the longest standing and time-tested automated process that fired an action based on Evaluation criteria and rule criteria.
• You cannot perform DML operation on Workflow rules.
• You cannot query from a database by Workflow rule.
• It is a Rules which will be helpful to update the same object or master object in custom master-detail relationships.
• For workflow rules, there is no Coding required.
• Workflows are also worked only after some actions.
• Workflow rules can send outbound messages that can’t be done using flows or process builders.