Ansible Core is a rpm package, that is comprised of several ansible binaries/executables (e.g. ansible-playbook, ansible-inventory, etc.)
What exactly was Ansible Engine? Was it an rpm package like Ansible Core? Or was Ansible Engine a name that was used
to refer to the framework of Ansible?
Has Ansible Engine gone completely bye bye?
Ansible Engine used to be a “product” where customers could buy a subscription for support and bug fixes for “just” command-line Ansible from Red Hat (if they had no plans on using the previous product named Tower). There is only one product sold right now, which is Red Hat Ansible Automation Platform. If you want a good comparison of upstream vs product there is an article here: Understanding Ansible, AWX, and Ansible Automation Platform but Engine has not existed for some time (IIRC pre-pandemic) so its only really referred to in Knowledge Base articles for a few existing customers that were/are on long-term support.
Technically… there is also “Ansible Inside” which is really meant for Red Hat partners for embedded plays (where their product offers functions/features ontop of Ansible): Red Hat Customer Portal - Access to 24x7 support and knowledge but this is targeted towards partners and would be invisible to most cutsomers.
Then I’ve erroneously been using the term “Ansible Engine” the last few years. I do find it easier to pronounce than “Community command-line Ansible”, though. 
maybe one of the Ansible-Core engineers will comment, but they probably just refer to command-line Ansible as “Ansible” to make it super short
Besides being the commercial name by which Red Hat sold subscriptions for the productized and supported version of Ansible CLI as @IPvSean mentioned, you could think of Ansible Engine as basically the product version of Ansible up to version 2.9.
Ansible 2.9 and below was a single package that included the Ansible CLI commands and the modules (what at the time was referred to as “batteries included”) , the modules were split into collections later and ansible-base/core was born.
Ansible Core (or ansible-core) is basically the same set of command line tools (ansible-playbook, ansible-inventory, ansible-galaxy, etc.) but with a reduced set of modules (“core modules”) and plugins. It carries on from the 2.9 version scheme, and currently is at 2.15.
Ansible Community Package on the other hand is a larger package, that includes community curated collections and depends on ansible-core to function. This is usually referred to simply as the ansible package, as that one will install the required dependencies.
ansible-core and ansible are available as different types of packages depending on your Linux distribution. In RHEL you will find the RPM if you have the subscription and repository enabled, in Debian and Ubuntu you will get the upstream community versions from their own repositories. In all cases you can install the current community “meta package” called “Ansible Community Package” with pip for example, that includes a community-curated selection:
pip install ansible
You can read more about Ansible Community Package and ansible-core in this doc.
True, but when I’m talking it’s hard for my interlocutors to hear the difference between “Ansible” and “ansible”, just like it’s impossible to distinguish between “AWX” (the product) and “awx” (CLI). 
Oh, I hear you! Ansible-land is full of loaded terms 
Which reminds me, the Ansible Glossary might come handy in case someone doesn’t know about it.
Okay, thank you for your reply Sean.
By the way, I enjoy your training video on
Ansible Basics!!!
Let me begin by thanking everyone who took the time to provide a response to my query. For your time and effort, I’m extremely grateful!!!
Before I composed this post, I read through each response, taking notes.
Sean commented: “Ansible Engine used to be a product …” So, my interpretation of that comment is that when Ansible Engine was the only game in town, it WAS a product. So if I were to go back in time, and someone were to ask me, "Trevor, what is Ansible Engine? I would, or should, respond by saying, “Ansible Engine is a product”. This is based on my understanding of Sean’s comment.
By the way, Sean thank you for mentioning the article, “Understanding Ansible, AWS, and Ansible Automation”. Fortunately I read that article about 2 weeks ago. Unfortunately, it did nothing to wipe away the fog regarding the question about what Ansible Engine is.
And just in case the mountain wasn’t already high enough for me to climb, Sean thought he might raise the incline by mentioning Ansible Inside. Ouch!!! That caused me to put my computer to sleep, and go for a bike ride to clear my head 
Leo said that I could think of Ansible Engine as basically the product version of Ansible. I wasn’t sure if that would permit me to say that Ansible Engine was a product or not.
Leo mentioned the Ansible Glossary. Thanks Leo for that suggestion. I’ve toured that page for so many days, I feel I could recite it in my sleep.
So you guys are now asking, “What does this guy want? We’re answering his question. Does he have a learning challenge?” That’s a fair question
I was hoping to get a summary response that would simply state:
Ansible Engine is …!!! For example, SSL is a protocol! Any way you slice it, that’s what SSL is. Now from there, I can fill-up 10 pages easily with additional information. But when all the layers are peeled back, SSL is a protocol.
Okay folks, I’ve used up enough bandwidth on this matter. Ansible Engine is no more. R.I.P. Ansible Engine!!!
When I can locate it, I’ll share a diagram that I saw about 2 months ago, that set off this firestorm in my little brain.
Again, thanks everyone for your time and effort. I remind myself before every post, that no one is obligated to provide a response to any question or comment that is post in the community. However, each of you were kind and considerate enough to entertain my query, and for that, a mere thank you seems so trite.
I didn’t get a one-liner to my query, but be assured that I absolutely came away educated!!! Many, many, many thanks!!!
The massive overload of the term Ansible is something we regret in core, but are powerless to fix.
As Ansible (community distribution) is installed via ansible (the pypi pakcage) but depends on ansible (CLI part of core) which lives at ansible (repo github.com/ansible/ansible) but it is confused with ansible (AAP … all 27? components) specially by people that don’t even know the CLI exists. So I always have to ask people to be specific.
/me goes to corner to cry
We’re doing our best to help that overload over here in the Community Team too! But crying does indeed seem appropriate 
Me who doesn’t even know what the word “ansible” means…
He, when i first started with Ansilbe you would get the “Ender’s Game” wikipedia entry as top Google result (now 10 pages down).
I’ve never cared for the wikipedia stuff. I do appreciate the effort made to contribute!!!
“Ansible Engine” is presenting Ansible only! If we see the exact definition of Engine; It is “An engine is some machine that converts energy from a fuel to some mechanical energy, creating motion in the process”
same way-An Ansible engine is a software that helps converting program to process with less effort avoiding the manual intervention & no human error on a number of managed hosts with faster approach.
This high level word Engine is used along with Ansible to make the techie beginners more confused about ANSIBLE! 
Few sites wrote:
–open source automation Engine
– Ansible is a radically simple IT automation engine
If the above is not correct, I request ANSIBLE to show the ANSIBLE ENGINE where it exists practically!