Well, there are no difference between western violin or eastern/ carnatic violins. All of them have same size, same build, same number of strings.
However there is a difference in tuning. Carnatic violins are tuned in C-G-C-G (sa pa sa pa)format. Which is set in accordance with singer's key and pitch. Basically carnatic violins are used to support vocalist. Western violins are tuned to play in orchestra or for background scoring. This is the reason why they have a high pitched tone