The 2nd, even though he's not flared looks more like a Delta, HMs usually carry their tails around a little differently.
Easiest way to tell a HM when you see one is their tail makes a perfect D shape and when it's flared with all the other fins there's no gaps between fins and they all overlap slightly.
Here is a HM:
I hope that helps a bit :)
Your first boy looks like a SDT as the tail doesn't quite make that D shape and doesn't quite tough the anal fin correctly.