I was recently asked if the Guardians of the watchtowers are the same as Archangels. The reason I was asked is because a lot of Magicians call angels to their circle or the Guardians of the watchtowers. It's a good question to ask, and since I've been doing my own work around the archangels of the quarters, I thought I would answer it.
The short answer is that the Archangels aren't the same as the Guardians of the watchtowers. They are each their own distinctive set of beings. Frater Barrabbas has an excellent book out about this very topic called Spirit Conjuring for Witches: Magical Evocation Simplified (Affiliate link), where he explores this topic in depth.
My own experience with the Archangels also doesn't suggest that they're the guardians of the watchtowers, but rather that they have their own distinct roles which should be explored in depth. In fact, this is why I always recommend doing thorough research on what spirits you'll work with so that you don't create this blending of function, which isn't accurate.
For example, one of the reasons you develop a correspondence table with a spirit you work with is because the correspondence table speaks to the relationships and associations that are relevant to the spirit. For example if we work with the archangel Raphael, what we're initially doing is learning about who that spirit is and what functions/associations/attributes etc are aligned with Raphael.
What happens as a result is that we build a profile that we use every time we work with Raphael. That profile allows us to not only evoke or invoke Raphael, but also connect with the powers that are associated with Raphael. We learn what those powers are by taking the time to build a relationship, but the benefit we get is that when we call Raphael up, we're also connecting with those powers. What Raphael does for us is mediate those powers so that we have access to exactly what we can handle and no more than that.
Circling back around to the initial question posed above, the reason its important to have a distinct understanding of the spirits in their own rights, as opposed to blending them together is because of what they represent and mediate. By understanding the function/role of Raphael in a separate context from that of a guardian of the watchtower, we can readily appreciate the role/function of each and employ each appropriately in our magical workings.
Now it could be argued that if a guardian of the watch tower and Raphael occupy the same quarter, won't they have the same associations? We shouldn't assume they will, because although they may share a quarter and some associations in common, there may also be specific differences. There's also the simple fact that if I work with Raphael that's who I'm working with. Blending the identities of spirits for your own purpose disrespects the spirits you're working with and also takes away from the potency of the connection.
I recommend that whatever system of magic you work with or create that you remember that the relationship you form with a given spirit is really a discovery of that spirit and what it represents, as well as how that relationship can be applied to the other spiritual work you're doing. Don't try to force connections...simply discover and be open to learning. The rest will reveal itself as needed.