I've seen many times in Linux, the version in app store is different from its website(usually outdated).

Yes, this makes sense, since most distros use a "standard release" system. The intention behind it is to keep your OS stable and only apply security patches at some point. If you want to have a system with always the newest software, you need to use a "rolling release " system. I think Arch Linux is the most popular (arch user btw). This is much more fun, if you know what you are doing. Otherwise you will end up with a broken system pretty fast. Ofc you can fix it, but depending on experience and skill something like Ubuntu is the better choice.