Understanding difference between qfrc_applied and xfrc_applied

[Hardwarize]

Intro

Hi!

I am a master student at UNED, I use MuJoCo for my research on generative human motion.

My setup

Mujoco python

My question

I'm very noob in the robotic and simulator field. I am not able to understand the difference between qfrc_applied and xfrc_applied. Reading in other places and watching some videos I understand that qfrc_applied injects torques/forces directly into the joint space, while xfrc_applied applies forces and torques in the 3D (Cartesian) space of each body. If you have a free joint both are not basically the same? and if you have a hinge join and you want to aplly torque with an actuator, I've seen that you should use qfrc_applied but don't you can get the same result with xfrc_applied?

Thanks in advanced

Minimal model and/or code that explain my question

No response

Confirmations

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