Email Marketing Campaign allows you to send a one-time mass (bulk) emailer to different segments of your customer database. 

A drip marketing campaign on the other hand allows you to send a series of emails (staggered over time) to different people based on the time they get added to the drip campaign. 

The following table will be useful in highlighting the differences between Email Marketing & Drip Marketing campaigns

Email Marketing Drip Marketing
Type of Email Activity Bulk/Mass emailer Staggered series of emails
Manual - One-time activity Automated Activity (One time setup)
Audience & Content Same Audience, Different content Different Audience, Used in cases where email content does not change very frequently
General Use cases Used for Promotions/Offers/Announcements Used to send Tutorials, Reminders, Tips, Guidelines

Used to move contacts down the marketing funnel
(Prospects -> Leads -> Customers & so on)
Example Email to inform all your clients about a new product you have launched Series of emails sent to someone who fills out the contact form on the website