That is a very big difference.
There's a big difference between Chinese and Japanese, yet they are both meaningless to me.
By slapping on a "Mehadrin" label, a local rabbanut
might be allowed to be more selective, but it is still usually all about marketing.
And while the argument has successfully been made that in Eretz Yisroel there is a meaning to the word "מהדרין" on Rabbanut Hashgochos, that doesn't automatically make any Hashgocho with the word "מהדרין" in it, even if it is from any given Rabbanut, any more trustworthy in my eyes. For all I know, they might be selective, and approve of things that I wouldn't dream of approving in my kitchen.
The two Hashgochos which are in a totally different league than all others in many aspects seem to be Badatz Eida Chareidis, and Rav Landa of Bnei Brak.