What is a Cohort Analysis?

Measuring users in cohorts provides benefits in the consistency of analysis and is a technique well applied in the offline world. It helps analyze the long-term benefit of specific groups of customers (for example, customers who first visited within a specified timeframe).

What is a sequence segment?

Sequence segments provide an easy way to segment users based on a series of on site behaviors. For example, customers who started on a specific landing page, visited some particular pages and ended up converting. 
User sequences now provide you with capability to define a sequence across multiple visits.