Question

although guitar and violin are stringed instruments. what is the difference in playing the two ??

Answer 1

Their sounds are different from each other.

Answer 2

I think the material of the strings should make a considerable difference. Violin strings have been made from sheep's intestines (and nowadays metals too), and guitar strings are dominantly made out of nylon or metal (like steel). I think the strings on the two instruments must have different build; their thickness and manner of making might greatly differ.

And as suggested in the other answer, the style of playing the instruments, and their individual builds should also cause the difference. Besides, their shapes aren't same too. So there can be many reasons for that.