Like I said both of them provide same test materials and conduct test procedures. Interviewers vary yes but they follow the same format on interviewing the test takers.
My interviewer was an American bloke who was married with a filipina that resides in Bohol. He was nice, very chatty and he made me feel comfy and confident. Don't believe the rumours that say filo interviewers give low scores, that's just a load of nonsense.