I can really recommend you to look at Free Software Foundation website[1]. In a nutshell: free software is like "free will", not "free lunch". It gives users four essential freedoms: to run it any way one wants, to study and modify source code, to redistribute copies and particulary redistribute modified copies[2].

As you can see, "open source" give s only half of those freedoms: to study code, it is not mandadory that you actually can modify it.

So, not all opens source software is free. Check out licence comparison and approvals page at Wikipedia.[3]

[1] https://www.fsf.org/ [2] https://www.gnu.org/philosophy/free-sw.en.html [3] https://en.wikipedia.org/wiki/Comparison_of_free_and_open-so...

You're wrong and as a matter of fact the definition for Open Source is more clear and a little more restrictive than that of Free Software:

https://opensource.org/osd

Thank you for the link. I was actually unaware of this organization. I was thinking that "open source" is more like a figure of speech, not ideology like "Free Software"

At the same time, we see a MongoDB example: a software, which definitely is open source, but also definitely is non-free.

Open source: source is freely available online.

Free software: free for modification, expansion or forking. Possibly free for profit (BSD license)

Source Available: Source is available but under restrictions. Locked room source viewing under NDA to confirm there aren't vulnerabilities for example.

Open source/free software: You can download, modify and re-release the source.

Source-available: You can view the source, perhaps freely, but can't modify or release your modifications.

This is easily searchable.

I'm not asking for lack of knowledge, but I was asking the parent as they needed to make the distinction.

Why? The FSF and the OSD make the distinction.