What s the difference between using a

the main diff is that you can call the former on pretty much any index (except the tree index lol)

tree_summarize is a technique for synthesizing a response, after the index has returned the relevant nodes

response_mode=tree_summarize also works with the tree index too!

I see, but then what exactly is summarize doing?

it's doing the same thing

but only for a tree index

response_mode="tree_summarize" will build a response with any index

I see, that's very helpful, thanks!