Laptops use the Windows operating system. (Pedants might point out that they're capable of using
any operating system, such as Linux, but all the laptops that you can buy in High Street stores come with Windows).
Chromebooks use the Chrome operating system which, like Android, is a Google product. They come with some apps pre-installed, which are listed here:
https://geekthis.net/post/chrome-os-default-apps/
If you want other apps then, just like with an Android device, you have to download them from the Google Play Store:
https://www.google.com/intl/en_uk/chromebook/apps/
Many Android apps will run under the Chrome operating system, but not all of them.
Chromebooks are designed around the principle that users will, for most of the time, be working (and storing files) "in the cloud". So they need a decent internet connection to get the best from them. The need to work"in the cloud" comes about partly because of the very small amount of storage space available on a Chromebook. The idea is that you store all of your documents, photos, videos, etc on Google Drive, or similar.
Some people love their Chromebooks but they're not for me. I want my files to be stored locally on a laptop (even if they're backed up 'in the cloud' as well).