Are these two solutions the same - built for the same purpose?
If they are not the same, what are the major differences? Any thoughts or hands-on experience would be appreciated!
I would say no.....but it depends on your needs.
ArcGIS Server | ArcGIS for Server
ArcGIS Online Help | ArcGIS
AGOL and/or Portal actually can work with ArcGIS Server.
You may want to mark this as a Discussion instead of a question, since you will get many comments (my guess) and there isn't any definitive answer, in my opinion. Done
I thought there would be others that would have already jumped into the discussion, but I'll add some more comments, from a long time ArcGIS Server user/administrator and shorter ArcGIS Online user/administrator (a few years) and a new (testing the waters of) Portal user/administrator. ...sorry and warning, I tend to get long winded.
How you might answer this question really depends on what is is you are trying to do, and what resources you have (hardware, cloud, staff), etc. Security and the ability to use the ArcGIS Online platform might also influence what you can use. For some, the in-house Portal is very similar to ArcGIS Online, but on-site vs in-the-cloud. I'm simplifying this a lot, and I've been told that calling Portal the on-site ArcGIS Online is not the message esri is trying to get across, but in my mind, that is still the easiest way to explain it.
Now, as a Department that has access to all three (plus OpenData and other ArcGIS Server features...not called extensions anymore) which now fall under the ArcGIS for Enterprise (AE) umbrella, we tend to use a combination of the items. Personally, if I had to pick just one of the tools from the AE set, I would still pick ArcGIS Server (and Desktop of course), but I don't think AGOL/Portal will replace ArcGIS Server, my opinion. ..Also, besides the names users, there is still a credit cost for some items/processes (but not all).
For one, although improvements have been made with the Level 1/2 named users, Your Guide to Named User Levels | ArcGIS Blog and we really don't have pricing yet, chances are shop will not provide a named user for every employee (at least not at this point). So, having a way to allow internal only, secure services to all, without requiring a name user, is something that I'm hoping to work out with a combination of ArcGIS Server and Portal. Time will tell if it works as I perceive it.
So, after this long winded rant, I do not see ArcGIS Online (or Portal) replacing ArcGIS Server. For some, maybe, but for the bigger organizations, not anytime soon.
Anyone else want to weigh in?
Aside from the named user login consideration that Rebecca mentioned, here are 2 big things ArcGIS Server has that ArcGIS Online does not [currently] offer:
Keep in mind: ArcGIS Server map services can be added to ArcGIS Online web maps. This offers you the additional functionality of AGS within AGO apps.
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