Are there differences between both? I know CWA is for Constant Wattage Autotransformer, but I don't know that does CWI mean...

CWI means Constant Wattage Isolated,the design is very similar to a CWA Ballast except the secondary coil is electrically isolated from the primary coil.

Yeah I found the answer in the Advance Trasnsformers website just after posting my question. Anyway thanks!

Due to isolation, the CWI uses more wiring, so has higher losses and/or is larger and heavier.

Due to isolation, the CWI uses more wiring, so has higher losses and/or is larger and heavier.

...and more $$$

I think CWI ballasts are the standard for high voltages such as 480V.

I think CWI ballasts are the standard for high voltages such as 480V.

The isolation allow grounded lamp shell, even if the input is connected between 2 phase - each of them is live respect to GND