Developer API vs Trader API Documentation Error

My goal is to integrate the Upstox API to create a basic trading platform for my application.
So Upstox offers two APIs which are Developer & Trader API, where the Developer API is used to create an app altogether.
Now when I click on it I am redirected to Uplink Business and when I scroll down I get the docs for the API I want to try.
Also I already have a demat account with upstox for generating the keys.
My question is, are the API calls for both Developer and Trader API are same, since I am being forwarded to same documenation?
Also currently the Authorize API call is being redirected to login to my Upstox account to generate the code in redirect uri. If someones else wants to create an account on upstox using my platform using upstox api will it still be possible?

Also it would be better if someone can reach me personally, if they dont understand my questions and want more reference on rishivrm0@gmail.com