Who I have the same questioned this topic

I primarily use wifi calling when I'm in my house due to the signal quality. I have been unable to find anything that explains the difference between when the phone displays Verizon or VZW WiFi. See screen shots. 

Can someone please tell me the difference between the two? Am I still in wifi calling if it just says Verizon? From the call quality, it seems I may have reverted back to LTE but it doesn't say that. 

I can't figure how to force it to go to VZW WiFi unless I shut off cellular data, which I do not want to do. Is it an iOS bug?