Google play website shows all Apps under "My Apps" as "Installed" even uninstalled ones I am looking at "My Apps" in Google Play Store and Google Play website.

In Google Play Store, it marks properly the apps that are currently installed as "installed" and the apps which have tried earlier and uninstalled shows up with a "x" mark that deletes the selected app from "My Apps" list.

But in Google Play website, it shows "installed" for all apps under "My Apps". 
Is there any option to see the uninstalled apps in google play store?
Encountered the same here. From my limited research it seems that it has to do with 'syncing' to Google Play when an app is uninstalled.
Your device just looks at which apps it has in the internal memory. Google Play website needs this info being synced to it.

So when you install an app it shows correctly on both platform. When you uninstall it and have a working internet connection on your phone, it also shows correctly on both platforms.
Now if you install an app and for example hard reset your device (or your device is by other means unable to sent to the server that an app is no longer on your device), then it still shows as installed in Google Play website. As far as I know, there is no way to make your device 'resync' the installed apps. Only way would be to install the app again and uninstall.