If you have a 1080p TV and 4k stick you'll notice a difference.
While a 4K video displayed on a 1080p screen won't be able to show all the detail that a 4K display could, it can still provide some benefits. The additional pixels in the 4K video are used to create a more detailed image, even though not all of that detail will be visible on a 1080p screen. This can lead to a sharper, more detailed image overall. Additionally, some 4K videos have improved color and dynamic range, which can still be apparent on a 1080p screen. So, in general, a 4K video can still be somewhat better than watching the same video in 1080p even if your monitor is also 1080p.