Difference between Goal and Objective

Firstly I don't accept the blunt assumptions in that article. The author seems to have run with one arbitrary assertion that goals are somehow broader and more long term than objectives. That's an opinion. And it's one that many people with a sporting background would disagree with.

As this is Scrum I really want to refer to rugby as an example, but instead I'll use association football (soccer), because the scoring is a lot simpler.

In soccer, it's pretty common for the top teams to talk about objectives such as winning the championship (or at least improving on their position from last season).

Whereas (depending on context), a goal is either the space surrounded by a metal frame and net that teams try to kick the ball into, or the score they get for doing so.

Many goals are scored on the way to achieving that objective.

In the Scrum Guide, the word "objective" is used exactly three times; and on each occasion, it appears in a supporting role, as more clarity is added to the Sprint Goal.

The Sprint Goal is crucial to Scrum, but I'd argue that the word "objective" is used in the same way that "list" is used to explain the Product Backlog. We could try to identify differences between the Product Backlog and the various ways lists are used, but I wouldn't spend too long on it, unless you see a way for it to help you get a better Product Backlog.

One very tangible way that I have used the word "objective" aligns with this part of the Scrum Guide

The Product Owner discusses the objective that the Sprint should achieve and the Product Backlog items that, if completed in the Sprint, would achieve the Sprint Goal.

Given that this is the first mention of a Sprint Goal in the description of Sprint Planning, it's reasonable to assume that the Product Owner will have an objective in mind, before the Scrum Team has crafted the Sprint Goal. In my experience, the Sprint Goal can match this objective exactly, but as it's the result of collaboration, it normally centres around achieving a slightly (or somewhat) different objective.

So a Product Owner might talk about the "upcoming objectives" during the Sprint Review out of respect for the Scrum Team's shared responsibility in crafting the Sprint Goal at a later stage.

Per my understanding as of now, a goal seems to be qualitative and outcome-focused whereas an objective is quantitative, measurable, and has a metric associated with it.

I am seeing my Scrum Teams trending towards increasingly ambitious, outcome-focused Sprint Goals, but they are still quantitative (such as "Increase adoption of feature X to 20% of customers"). I've also been part of teams that never made it beyond the Sprint Goal being the achievement of an output (and sometimes a very rigid output at that) like "Implement the new design of feature Y".

With OKRs, the timeframe is usually longer than a single sprint, and so the measurement of quantitative outcomes is often a lot easier; but the objectives themselves are usually just motivational and transparent expressions of the purpose. Key results are used to enable better (ideally outcome-focused) discussions about how right or wrong we were in what could be achieved, and what to do next.

A Sprint Goal is one of the objectives a team ought to have; others include achieving Done and making improvements. In Scrum, it may be helpful to think of an objective in terms of a commitment which is being made.

Sprint Goal is a term of Scrum. Both belong together and the Sprint Goal is given by the PO in order to give an objective that he wants to achieve with the Development Team.

But if the author used goal instead of objective, it would be a horrible sentence, having goal twice so close together.

My understanding of goals and objectives is the following.

Goals are the outcome you hope to achieve, objectives are the means/actions that you feel are necessary in order to achieve the goal.

Using @Simon Mayer's sport analogy, putting the ball into the metal framed, netted area is the goal and what you are rewarded to do.  Objectives to achieve that goal are pass the ball so that it can't be stolen easily, spread your team so that it is difficult to cover everyone, move the ball forward as much as possible, no one should ever stand still as they strive to be open to accept the ball, everyone should strategically move in order to put someone in position to shoot the ball towards the framed area, first person with a clear shot takes it while everyone else moves into position to capture any rebound and potentially reshoot. 

I do not feel that one is considered more long term than the other.  They are both needed to help a team realize what they want to achieve, why it is important to achieve and how each individual plays a role in achieving.