Second stage vs Octo

[breathe_nitrox]

Just wondering, are there any differences between a second stage regulator and its octo equivalent. For instance is an Oceanic Alpha 7 octo just a Alpha 7 2nd stage with a different color purge, or are the octos a cheapened version of there 2nd stage equivalent.

 

[joens]

A lot of times the main second stage is externally adjustable and the octo is not.
joens