Shiite V Sunni
Not exactly. Its Pakistan vs Baluchis, in this particular case.
The Baluchis are a minority group that live on both sides of the border but mostly in Pakistan. The Baluchis want independence from Pakistan (some of them anyway).
Baluchis are almost all Sunni- 99% or so.
Iran harbors Baluchi separatists.
Baluchis were deeply involved in Al Qaeda. Khalid Sheikh Mohammed is a Baluchi.