Caulerpa taxifolia or not taxifolia

On the forums they say that the algae on the left is taxifolia, yet the exact species with that name is the one on the right?

The one on the right grows as a vine and not overly thick in coverage with a bigger leaf, persay, and the other will form a very thick layer of its self as grows over and over it self.

They grow totally different to each other and one needs substrate to grow well and the other does not!

I got the proper name of the thicker growing small leafed one from the museum years ago but have no idea what that name is now, but I will chase it up.

There is so much info out there that is not info, just opinions and ways to direct you who knows where some times!

The pic is of both fully matured,healthy and from the same environment, my scrubber.

Here make your own mind up on this pic!