Is UT in PinePhone same thing than in another phone?

[natasha]

I discovered Linux phones by finding pinephone. However, I see that UT has been before than PinePhone. So, if UT is installed on another phone (e.g. Oneplus one)  is that already a Linux phone? Or does it still need some android software?

If so, what makes PP so special? or it isn't?

Is anyone kind enough to share some thoughts?

thanks!