Feel free to browse yourself since you are so enlightended.
http://www.cfr.org/issue/456/
Please note the sheer number of groups with Islamic, Islamist, Martyrs, and such versus the others.
They are in the news more because of the sheer number of their activities and their numbers period. They dwarf the rest. Have read through. Only the IRA can come close to meeting the numbers that the Islamic one put up in murder.
Now I will take 2 groups from each. 2 Muslim; 2 Western
Well lets start with the IRA;
This is the the Splinter groups from the Provisional IRA.
http://www.cfr.org/publication/9240/...dcrumb=default
Experts aren’t sure, but they estimate that there may be as many as 150 active members of the Real IRA, around 100 active members of the Continuity IRA, and perhaps fifty of the Irish National Liberation Army. Each group is small enough to be vulnerable to informers, both from the IRA and from British or Irish security forces.
At it's height the Provisional IRA was at 300 or so members. But they have given up the fight. So we'll go with the splinter groups.
ETA: Who has recently decided to stop any and all terrorist activities. No numbers but then they were considered to be smaller than the IRA and certainly less effective.
http://www.cfr.org/publication/9271/...paratists.html
Hezbollah;
http://www.cfr.org/publication/9155/...hizbullah.html
How big is Hezbollah?
Its core consists of several thousand militants and activists, the U.S. government estimates.
Armed Islamic Group(known by its French acronym, GIA)
http://www.cfr.org/publication/9154/...islamists.html
The GIA is now thought to have between a few hundred and a few thousand operatives and is listed on the U.S. roster of foreign terrorist groups.
I rest my case.