Drips allow you to send texts or emails with certain triggers at particular intervals, whereas campaigns allow you to mass message at the time you create the campaign or whenever it is scheduled.
Drips can be set up from the marketing page by clicking the marketing dropdown menu from the left-side menu and selecting either SMS or email.
Campaigns can be set up by clicking the campaign button on the left-side menu.
Only one campaign can be scheduled to send to a lead at a time, and campaigns cannot be sent to leads that have received an automated message such as a drip message, initial preset text, or another campaign within the last 48 hours.