UPDATE: I also posted this question on Reddit. I seem to have found a legitimate answer from there. I copy/pasted it below for those who are still following this thread.
youngermann 35 minutes ago
I am pretty sure APFS(Encrypted) == FileVault Encryption
I did not choose APFS Encrypted option when I format my boot drive for HS install. I formatted it to just APFS.
When the FileVault option screen comes up. I chose to turn on encryption. After the install, Disk Utility shows the boot volume now as APFS(Encrypted).
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cbackas42 27 minutes ago
This is correct. "FileVault" is essentially the marketing name for encrypting the boot volume.
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Guitar_t-bone[
S] 19 minutes ago
Thank you very much for the clarification.
Though, I do wonder. Given the fact that both HFS+ and APFS utilize FileVault, what is the difference between the acclaimed APFS "native encryption" and HFS+ "non-native encryption"?
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cbackas42 14 minutes ago
HFS+ does not support encryption. In order to accomplish it, a whole new layer called "CoreStorage" was created. CoreStorage can be encrypted, and HFS+ can live inside CoreStorage. CS is sort of a giant hack to graft new capabilities onto an old OS. Using CS Encryption on your boot drive is called "FileVault", but you can certainly CS Encrypt pretty much any drive you want - it's the same encryption.
APFS supports intrinsically. I'm not sure if it's "stronger" encryption than was CS used or not, but it's certainly more flexible. We aren't seeing the full extent of what it can do just yet (things like per-file encryption) - maybe in future releases. But it's the same situation, it's called 'FileVault' when applied to your boot volume, but you CAN encrypt any volume and it's the same encryption.
They're just using FileVault as a blanket term so that end users have an idea of what they're getting without having to understand the confusing situation underneath.