I am currently about half way through a 5 year diaconate formation program, so I’ll share my view from the midst of it.
First, the academic education will depend on a given program. Some diocese have their diaconate candidates attend classes through a seminary while others either roll their own classes or perhaps use faculty from a Catholic University. Some diocese have an option for their deacons to come out with a Masters in Theology and others don’t.
I regularly speak with a seminarian who started at the same time as I started formation and can say that the full blown theology degree is more in depth. For instance we spent 6 weeks on the Gospel of John whereas he had a 16 week semester long class on the same topic. In many cases I would say that good programs will cover the same material but more as an overview or survey fashion.
That being said, we are still held to graduate school level research and writing in my program. So while we meet once a week for a 3.5 hour class, I regularly have 10+ hours of reading outside of class as well as time for writing and researching papers.
One thing that is very different though between a theology degree and diaconate formation is that academics is only one piece of formation.
Formation consists of four pillars: Theological, Human, Spiritual, and Pastoral. A theology degree covers the theological aspect, but does not touch on the other 3 aspects of formation. Formation also works on our personal flaws and how we relate to people (human formation); our personal relationship with Christ and interior prayer life (spiritual formation); and how we bring the light of Christ to others through ministry (pastoral formation). All these things are additional time spent outside of class.
It’s important to remember that being a deacon is a call and to successfully answer that call requires more than simply knowing theology. If you are thinking about the diaconate as a way to learn more you might be missing the point. We learn theology to help us in ministering to God’s people. The education is not the end goal, but simply part of what we need to fulfill that call.
One final thing to remember is that the diaconate is a vocation just like marriage, the priesthood, or religious life. As such the Church and candidate both are in ongoing discernment if a man has a calling. That means that if you are only focused on the education that you might discern out if you neglect the other aspects of formation. Several times a year we meet with the director of formation and the theological aspects are only a very small part of the discussion.
If you are called to the diaconate then by all means take advantage of the education it affords, but it is a grave mistake to think of either seminary or diaconate formation as an alternative to other educational avenues.
The key question to ask yourself is if you want to study for your own sake or is it to serve God and His children?