I've been lucky to coach and train in both agile marketing and software development, so I have a pretty clear picture of what's different (and what's the same). Here are a few noticeable differences that I've personally witnessed between agile for marketers and software development teams.
The software industry has had the Agile Manifesto that hasn't changed in nearly two decades. The marketing community decided to create a similar, but differently worded Agile Marketing Manifesto that more closely aligns with their world.
The Agile Marketing Manifesto is more loosely written and is subject to change. You'll see this disclaimer in it:
"While we made some important decisions at SprintZero, this is a work in progress. We will apply our own process to publish this manifesto, measure the results, learn from the feedback, and adapt and iterate."
A few key revisions for marketers are:
Adaptive and iterative campaigns over Big-Bang campaigns
Many small experiments over a few large bets
The process of customer discovery over static prediction
In software development, the most widely used framework is Scrum with two week sprints. In marketing, Kanban or Scrumban (a little bit of both Scrum and Kanban) are the most popular. I have seen pure Scrum work nicely in marketing as well. A lot of marketing teams go with one week sprints due to quickly changing priorities and turnaround times. Companies that are more traditional and are used to projects taking months find Scrum with two week sprints to be their best bet. If you're wondering why there is this difference from software developers to marketers in preferred frameworks, here are a few observations:
Marketers often find Scrum to be too rigid if they are used to a very free flowing way of working. This is especially true in agencies, startups and smaller companies.
Social media and other forms of digital marketing require almost immediate customer response times, so planning a one or two week sprint isn't doable.