The difference being that this is about protecting sensitive data like trade secrets, in a complex ecosystem that is impossible to fully oversee.
Many western governments have banned Huawei from 5g network components for the same reason and that is solid reasoning.
But with TikTok it is a very different story. Nobody needs to use it. People are using it voluntarily. In regards to steering people to bad content through its algorithm, it is no different from Facebook or Instagram. The argument @Viking_Hippie made is valid.
It is not about preventing foreign or private influence that his harmful to the citizens. It is about controling that influence.