Muse shipgirls is a idol variant to compare to the original shipgirls however it's NOT a skin,it's a seperate of the original version for example
Akagi
This is her original version
Akagi Muse
This is her Muse Variant
Some characters have their own Muse Variants however there some changes:
SSR original to become Elite Muse Varient such as:
Even including some Priority Ships become SSR Muse Variant like: