Well, concepts can be discussed at length and it-s quite often that you can't say one is 100% right while the other is 100% wrong.
This is why, working with customers, I ask them to express their needs from an end user perspective rather than using technical wording.
In your case, you start with "alias" word but looking further, you want to
distribute mail sent to one single address to multiple recipients. Am I correct?
If yes, then your need is similar to distribution list feature. In order to decide whenever you do need distribution list or if mail address associated to group is suitable, we should go one step further and check:
- how group is expended
- are group members mail addresses visible once mail received? Does it matter?
- How to reply? to Who?
Here again, from theoretical standpoint, approach is not to play with technical concepts but to describe what your needs are.
My view is a bit truncated however: enough debate with the pure theoretical stuff
If you know that, at the end, you will do with Zentyal, another way is to look at Zentyal feature and select the one suiting the best, perhaps with some trade-offs. This assumes you understand impacts of choices you make.