Risotto rice and Basmati rice are both rice but the difference is that they are different types of rice.
When basmati rice cooks it elongates more than it plumps as it cooks and basmati rice is also lower in starch than other rice including Risotto Rice.
Risotto is also a type of rice dish but uses a different type of rice for the risotto dish.
Risotto Rice is made using rice that is either arborio or carnaroli rice.
Risotto rice dishes are also cooked differently than regular rice dishes are.
To make a good risotto rice dish you need the type of rice that's short to medium grain in size, plump, and has a high amylopectin (starch) content.
Otherwise the risotto dish won't turn out as good.