I mean...they're still 720p/1080p vs 3DS' 240p, the difference is obviously more than a little noticeable. The Switch is already better in several ways, again I'd say the only thing that isn't better yet is the software library. The 3D itself was 3DS' defining feature as a portable, and it's nothing to write home about.
To a certain extent, hardware doesn't matter in gaming consoles. A good library is much more important. The 3DS does have a terrible display resolution, for example. But the games make such well use of the display, you hardly notice it after playing and becoming emerged in the game (which is very easy on XL systems). Not to mention there's a couple areas that the Switch can never beat the 3DS in, such as portability. The Switch is a great system that will take off even more than it already has very soon. I don't regret purchasing mine however Nintendo needs to start releasing more defining titles for the system such as BoTW, ARMS, and Odyssey.
In the mean time, the 3DS is overall a better system. It's decently powerful (for a Nintendo portable at least), it has the entire 3DS and DS library available to it, and the games it has have already become iconic in themselves (Pokemon XYORAS, NSMB2, SM3DL).