A:Answer Hello! When it comes to cleaning, both Philips Sonicare DiamondClean Smart 9700 and Sonicare 9900 Prestige toothbrushes are identical as they come with same modes, except that the Sonicare 9900 Prestige has Sensitive. Also, the Prestige Toothbrush has SenseIQ technology where it senses, adapts and cares on your brushing routine. The sensors also keep an eye on how long and how often you brush and adjusts intensity when you push too hard, while the DiamondClean Smart has a scrubbing sensor that gently reminds you to reduce scrubbing and alerts you when you're pressing to hard. In terms of accessories, the Prestige toothbrush uses charging puck and charging case, while the DiamondClean Smart includes a charging glass and a charging case.