I think it's either parent project or parent experiment you don't need both.

AgitatedDove14 The question is whether it's done post-experiment or not.
After you conducted experiments for a few projects and you want to organize it our way of thinking works.
If you wan't subversions as you go on with the experiments that are conceptually different that they require a different project you're doing something not very organized. In that case the other option will be better, not my style of work.

let's call it an applicative project which has experiments and an abstract/parent project, or some other name that group applicative projects.

That was my way of thinking, the guys argued it will soon "deteriorate" into the first option :)

PompousBeetle71 that actually brings me to another question, how do you feel about "parent" experiment ?

Hi PompousBeetle71 , this actually fits with other feedback we received.
And for that reason it is already being worked on! 🙂

I have a few questions as we are designing the new interface.

I think our biggest question was, are projects like folders?
That is: I can have experiments in a project, but also sub-projects?
Or parent projects are a way to introduce hierarchy into the mess, which means a project has either experiments in it, or sub-projects, but not both
(obviously in both cases one case move projects from one "parent folder" to
another)

What do you think?

AgitatedDove14 Good to know! 🙂
I think it's good the way you described it (the second option).
let's call it an applicative project which has experiments and an abstract/parent project, or some other name that group applicative projects.