You’re right in that it looks similar to React, but it is also true that this kind of API is (declarative component tree composition) now very wide-spread and popular, and React was not the first to implement or adopt it (I feel like the person referencing Qt maybe meant Qt Markup Language specifically).

The way all of these frameworks differ from each other is both very slight in superficial details (think two-way binding or slots) and very, very strong in the basic implementation (i.e. the diffing or reconciliation algorithm).

So, yes, a lot of these look similar these days. But saying that they work the same is oversimplification in my opinion.