thanks for the great question!

I haven't had the time yet to dive into the details of L402 but as far as i know the main difference is that L402 is stateful.

Meaning that you pay an invoice and you receive back a macroon that grants you access for the next n requests. The server has to keep track of the state, to ensure you don't overdraft.

I think one big advantage of this is that macroons can be used for granular authorization which gives more control if you need to be able to lock specifc things down.

PROXNUT is stateless, which means every request is completely isolated from all other requests. You need to provide valid ecash on every interaction, and there is no linkability (other than network level) between the requests.

The advantage for users is that they benefit from having the 'the data monopoly' on their side (no state keeping on server), and at the same time the provider benefits from a simpler setup.

Another advantage is, ecash is centralized and backed by 'anything', so it is easy to have a system where tokens are representing something other than cash.

Ecash has a very low overhead (even compared to lightning, where you have to rely on the network liquidity and things like that) which makes a lot of sense for high frequency payments.

I hope someone that understands L402 can correct me if i'm wrong, or give their POV on the differences!