Algorithm: method for solving a problem.
Data structure: method to store information.
Algorithms + Data Structures = Programs.
Data structures such arrays, stacks, queues, trees and hash tables and their use cases. When to choose a linked list over an array? Should I go for a hash table or a balanced tree for my application? These are the kind of decisions you learn to take during the course.
Algorithms is typically more theoretical (lots of proofs!) and focuses on asymptotic time and space complexities of common algorithms. You also learn various approaches to tackle problems using strategies like Divide and Conquer, Greedy, Dynamic Programming, modelling your data as a graph and so on.