I think you are suffering some confusion here.
The Samsung Tab 7 is a standard Android tablet running the Android operating system and has access to the Google Play Store for loading apps.
The Chromebook is a laptop, and there are variants available from a number of manufacturers, and it runs Google's Chrome operating system and newer (and current) versions also have access to the Google Play Store and will run Android apps. It does not run the Microsoft Windows operating system although it is possible to get Microsoft applications to run on a Chromebook, the easiest way to being to download the Play Store versions of MS's software - things like MS Office.
Both would probably meet your son's requirements but there are other factors to consider such as portability. The Chromebook will be larger and heavier than the tablet, just as an example. You might find this article of some interest - https://www.androidauthority.com/windows-on-chromebook-1145337/ . Except I would completely ignore the later part of the article where it gives generalised instructions for installing the MS operating system on a Chromebook. That is not something for the faint hearted !
Chris Cosgrove