That's the major difference. Israel may have them, in the same way that the USA, China, Russia and France have missles and nuclear weapons - but have they declared an intention to use them without cause? I don't think so. Take a look at Hizbollah's web site or the official media of the Syria.
Firebomb thrown during demonstration in northern Israeli town of Umm al Fahm (Haaretz)
from the article: 'Syria helped Hezbollah amass some 40,000 missiles'