From my reading Hudson's Superimperialism is an more an extension of Lenin's Imperialism, based on how material conditions had evolved over the interim fifty years and the lessons learned from (at initial publication) the first generation or so of US dollar hegemony. To simplify it maybe too much, it adds a monetary dimension to the already established framework of finance capital being the driving force behind imperialism.

Superimperialism is indeed the same English term often used for Kautsky's Überimperialismus hypothesis. Yet apart from the initial parallel of a global cartel, ie. dollar hegemony, I don't see much of Kautsky's ideas represented in Hudson's work, but I'm also not terribly familiar with überimperialism.