What is the difference between Process builder and workflow?
A pretty complete overview with examples of which automation tool to be used in which case can be found here.
In short, you can do everything you can do with workflows using process builder as well, except for sending outbound messages with point&click. With process builder, you can also update all child records starting from the parent record, which is not possible with workflows (only vice versa is possible using cross object field updates). I've heard rumors that process builder will replace workflows in the future, which seems a logical step to take for sfdc.
You can use the Process Builder to perform more actions than with workflow:
- Create a record
- Update any related record
- Use a quick action to create a record, update a record, or log a call
- Launch a flow
- Send an email
- Post to Chatter
- Submit for approval
- Invoke a process from another process
- Call apex methods
But the process builder doesn’t support outbound messages.
Workflow does only 4 actions
- Create Task
- Update Field
- Email Alert
- Outbound Message
More information here
From Salesfroce Docs
Workflow
Workflow enables you to set up workflow rules that identify what kinds of record changes or additions trigger specified workflow actions, such as sending email alerts and updating record fields.
Visual Workflow
Visual Workflow enables you to create flows, which are applications that are user-triggered instead of event-triggered. Unlike Workflow, which always executes rules and actions behind the scenes, Visual Workflow offers screens for displaying and collecting information from the user running the flow.
Process Builder
Process Builder can be utilized to automate all workflow actions (with the exception of outbound messages). Traditional workflow can still be utilized in parallel, however, Process Builder gives you the ability to do things that workflow can’t. Although, somewhat of a double edged sword this puts some very powerful tools at the disposal of an experienced administrator. - See more at: http://gearscrm.com/overview-of-salesforce-process-builder#sthash.cp8hBLES.dpuf
Here is the good comparison https://developer.salesforce.com/docs/atlas.en-us.salesforce_vpm_guide.meta/salesforce_vpm_guide/vpm_faq_workflow_comparing.htm http://www.runconsultants.com/blog/comparing-salesforce-workflows-to-lightning-process-builder/ https://help.salesforce.com/HTViewHelpDoc?id=vpm_faq_workflow_comparing.htm