Questions after Vray RT vs. ADV Test

Hi guys. I was watching the amazing work done by Tomasz Wyszolmirski recently and I decided to make some quick tests based on his scene type. Here’s a small video of the results I found (no audio).

VIDEO_POST

Note* The results are shown from the sam Pixel . My questions are:
1.- Why when Caustics are ON, the Color Float value decreases so much? That affects the Glare creation and the ball looks opaque inside.
2.- Why Color Float changes values from CPU to GPU ? (GPU gave me the higher values).
3.- Why GPU makes different IOR effects? I mean, the refractions looks different when are made with RT-GPU.
I hope to read some of your comments. Thanks guys!

MARIO CAMERAS