Reasons for difference in freed spaces after package uninstallation [duplicate]
Actually when you install a package you get other packages(known as dependencies) which are required by the desired package. But on uninstalling only that specific package you mention gets removed. Hence the storage is still occupied by dependencies. You will have to use sudo apt autoremove to remove dependencies. However it too doesn't remove all the dependencies you installed with a particular package in case they are independent packages in themselves.