When Sony announced the XB900N in May, all the promotional images seemed to show a very similar design to the 1000XM3. While that is true in some regards, you won't be mistaking the two in a lineup. The outside of the earcups is where they're most alike, with the XB900N having very similar touch-enabled pads. This area is one solid piece on the XB900N though, where the 1000XM3 has a few nooks and crannies that separate its sections. Still, it's a departure from the previous Extra Bass headphones that had mostly flat circles for the earcups. The headband also has far more prominent Sony branding emblazoned on it.
Touch controls on the XB900N work a lot like the ones on the 1000XM3. Those controls will allow you to adjust volume (swipe up or down vertically), skip tracks (swipe front to back horizontally) and pause music (tap in the center). Tapping the center of the touchpad will also answer or end a phone call. The XB900N is the third pair of Sony headphones I've used these gestures on, and they're still frustrating. Often I'll pause the music when I touch the earpad to adjust the volume or change tracks.
There's also a "quick attention mode" that instantly lowers the volume to a low hum when you need to speak or listen to what's going on around you. It's really handy, especially if you're in an office or need to say a few words during your commute -- times you'd otherwise want to block out the world. To activate it, you cover the right earcup with the palm of your hand; it's one of the onboard controls that consistently works well
Sony gives you the option to have a dedicated Google Assistant or Alexa button on the XB900N. However, that luxury requires sacrifice. You'll have to give up the button that typically cycles through noise cancellation modes (on vs ambient sound). It's a half-step to a real solution, but hey, at least you have the option. You also have to choose to replace the noise-cancellation control with a virtual assistant on the pricier 1000XM3 too, so splurging won't necessarily remedy the issue. Honestly though, a lot of headphones have a dedicated button (or at least a specific gesture) to summon Google Assistant. And you shouldn't have to sacrifice functionality to add a basic feature like this.
Sony really nailed the comfort on the 1000XM3, and it did the same on the XB900N. It's basically the same weight (0.03 ounces lighter) with a cushy headband and soft, yet sturdy earpads. The tension of the headband is nice as well. It secures the headphones around your ears so the noise cancellation can do its job, but it never feels like it's pinching your head too much. These are headphones you can wear for hours without feeling like you're forcing yourself to do so. And that's essential if you're using the XB900N for travel.