Thank you for your explanations, Dust Rider.
I didn't look at this thread any more on DAZ forum because I didn't understand well the Octane render's advantages compared to that of Carrara.
Now that I understood well thanks to you, I realize that it's especially interesting for still images because in animation, one uses sometimes hair, also for grass etc...and if we wants to keep a homogeneity in the sequences, it isn't possible in this case.
I have two questions all the same:
1-What about particles, clouds etc.?
2- Does we have obligatorily to use the plugin for Carrara or can we do the work directly in the standalone version ?
I post this here, because they are to much specialists in the DAZ forum and I'm afraid that my questions are too basic...
Thank you again.

PS: your render with the Stonemason towers is very impressive !