I dont think there is a big difference between both.
My opinion is that run context give us more flexibility, but the legacy system forced developer to keep some sort of separation between client and server sides which is a good thing most of the times.
Reading this article should give you enough infos.
However, if you want to learn even more, feel free to create a post in the “dev discussions” category.
You’ll get more reviews by doing so.
Anyway, it was a pleasure to help you as much as I can.