Acans, how to tell the difference between species.

[Barrett]

I was wondering how to tell the difference between acan species, I just moved a few frags from my coral qt into my DT and it got me wondering what species I actually have, I got them at a local coral swap and didn’t think to ask.
Acan #1

Acan #2

 

[Shep]

Both are Micromussa lordhowensis (used to be acan but the species got changed awhile back)

 

[Barrett]

Both are Micromussa lordhowensis (used to be acan but the species got changed awhile back)

How do you tell that, what are the differences between species?

 

[Shep]

The heads/polyps look different.
Lords: look like yours


Acan echinata: look like this

 

[Barrett]

The heads/polyps look different.
Lords: look like yours


Acan echinata: look like this

Thanks I have been looking around and haven’t found any answers.