There are a lot of jihadis in Syria, along with lots of rebels.
One thing I've noticed is that for the tens of thousands of jihadis, there are darn few reports of suicide bombings or even IEDs being used.
I'd forgotten a point I'd made often enough in the Iraq War--the use of IEDs was a drop down the escalation ladder of insurgencies. A successful insurgency would start with mines and small ambushes, and as they gain momentum start using larger units until they have infantry fighting like conventional units, including heavy weapons support.
In Iraq, losses in firefights led the Iraqi insurgents and jihadis to the point where you rarely saw them attempt to fight in even platoon strength. No, they soon fought their war with IEDs and indirect fire, for the most part. They were well-financed with access to explosives and skilled bomb makers, which made their campaign bloody. But it was a loser's war. And we beat them.
In Syria, the rebels and jihadis are pretty numerous and hold a good chunk of Syria. They fight to contest ground more than they fight to harrass occupiers. So there are fewer of the attacks we associate with Iraq and, to a lesser extent, Afghanistan.
Although with Syrian government forces advancing in the west along the Lebanon border, I suppose it makes sense for us to see more mines/IEDs and suicide bombers used against the Syrian forces.