Political designations become meaningless if the overlap means x and y are the same, in this case liberalism and leftism which have very different intellectual and public histories. Yes, the overlap is there and it's important to recognise it and to engage it and sometimes ally against further forces but they're not the same. Leftism is a specific designation for redistributive economic policies, you can be a conservative leftist and many have been, it just happens that in the west liberal leftism is more common. You don't have to be a randian lunatic to not be left wing, you just have to be against leftist economics, namely against socialism. Harris is broadly an interventionist capitalist, i.e a liberal. There's MPs in the British conservative party who would vote against moving away from free at the point of service healthcare or who voted to legalize gay marriage etc. But it would be silly to call them leftists.