Are these ultrasonic toothbrushes actually using ultrasonic waves? I have an expensive sonicare toothbrush and a cheap noname $10 "sonic" toothbrush from the su

Are these ultrasonic toothbrushes actually using ultrasonic waves? I have an expensive sonicare toothbrush and a cheap noname $10 "sonic" toothbrush from the supermarket and can't really tell the difference between both. Both feel like a standard toothbrush with a phone vibrating motor put inside.