Sprint MNVOs

Question: Just talked to my wife's mother who has a Kyocera feature phone(in Oregon) whose account I switched from Tello to TPO about two months ago, and today she said that it "seems" as if the phone worked better on Tello than it does on TPO due to some dropped calls on TPO. This may also have happened even if she still was on Tello, but given that she has been using the phone in the same place, near the same tower on the Sprint network, I was wondering if the two MNVOs mentioned would make any difference in her call service or reception, something like using a different band or whatnot? I'm not up to speed on such things and was wondering if there would be any difference between the two Sprint carriers. Thanks.