Simple. It's weird how across the site, it's different.
In some pages, it's "Shape". In others, it's "Type". STILL others, it's "Length".

I did my best to find all instances on site, and even on the wiki, where it is listed.
In most cases, it seems to be "mane type", but not everywhere.

My suggestion: Just pick one word for it, it's weird how it changes so much.

Why does it matter?
It doesn't. Not really. BUT, it's a consistency thing, and most sites do not want to have a ton of inconsistency, as it makes them seem lower-quality.

"Shape" instances: [7]

"Length" instances: [4]

"Type" instances: [5]