difference of alpha texture

[LilyChocolate]

I want to ask about alpha texture on mesh object.

About a phenomenon to be seen in HAIR in particular.

It becomes transparent when I stack the object which set up alpha texture → image①

but there is the object which does not become transparent even if stack alpha texture → mage②

image : https://prnt.sc/nabztj

What are these two differences?

Is it not alpha texture?  Is it a problem of texture?

Is any setting necessary before/after uploading it?

Please instruct me on what I should do.