Difference between sprint backlog and sprint goal?

Question

One of the questions while PSM I™ Preparation Quiz which I was unable to digest was,

What provides guidance to the Development Team on why it is building the Increment?

1. The Sprint Backlog
2. The Product Owner
3. The Sprint Goal
4. The Scrum Master

For this I selected the "The sprint backlog" as appropriate answer but it turned out wrong. Correct answer is "The Sprint Goal" with the explanation as

"The Sprint Goal is an objective set for the Sprint that can be met through 
the implementation of Product Backlog. 
It provides guidance to the Development Team on why it 
is building the Increment."

My question over here is what is the difference between Sprint Backlog and Sprint Goal?

I have tried googling around to understand this but I was unable to get to any conclusion. Please suggest!

Answer 1

Great question! It sounds like you may already know this, but for anyone else, the Scrum Guide says this about Topic 1 in Sprint planning:

During Sprint Planning the Scrum Team also crafts a Sprint Goal. The Sprint Goal is an objective that will be met within the Sprint through the implementation of the Product Backlog, and it provides guidance to the Development Team on why it is building the Increment.

A sprint goal might be something like:

A user will be able to see a list of recent transactions on their account and search that list.

Then the team brings the backlog items in that fulfill that goal. Many teams pull in a number of backlog items that may or may not have some coherent theme and then set the goal of finishing the work. The difference between these two approaches is subtle, but it comes down to outcome vs output. The first one focuses on creating an outcome for end users. The second one focuses on output (work being done rather than value being delivered).

Something else interesting about this sort of sprint goal is that it is in some times possible to deliver the sprint goal without delivering all of the backlog items. This is a little unintuitive, but when things don't go as planned in a sprint, a great team can rally around the sprint goal to find a new way to reach it.

Answer 2

Excellent question. This is one of the topics that result in highly opinionated discussions when really it is clearly defined in the Scrum Guide.

The Sprint Goal is therefore an objective that needs to be achieved by the Team during the sprint through the implementation of part of the Product Backlog.

The sprint backlog is a stream of work items picked from the release backlog and planned for the current sprint. Committing to a planned set of backlog items is anti-agile, when you do so you are not accommodating for any change to the sprint backlog during the sprint development. Stakeholders and the Team will therefore have to wait until the sprint is over to make any changes to the backlog items or its scope. Agile came into existence to solve this problem amongst many others.

Sprint goal should also not be confused with Planned Velocity. Velocity is a metric that helps in predictability and management of the release.

A crude example would be a team of relay runners running laps. Every time they cross the starting point they are given a bag that weighs different, new hurdles they have to jump on, tight ropes they have to balance, help from team mates to climb a wall, etc. Thus each individual runner's lap time differs. No single runner can guarantee their own lap time nor can they guarantee the lap time for their team mates. The total lap time of the team will vary based on various factors. Velocity is therefore just a tool to measure if consistency can be achieved and how predictability can be improved for the long term goal.