I had the same thought as you a couple of weeks back. Googled it and apparently you switch between the two in the app.
However, I couldn’t find where so I got hold of a Uber support.
As ridiculous as it sounds, you have to onboard again, and also get another DBS check to sign up for Uber eats.
I explained to them I was already a driver on the Uber platform. It doesn’t matter. You still have to go through all the sign up process again.
I said I can carry people around no problem, but now if I want to deliver a kebab or a pizza I’ve got to get security checked again.
Ridiculous and told them to poke it up their arse.