PAF is getting F-16 Block 52+ (PLUS) , not F-16 block 52. The first Block 52 + (PLUS) was delivered in 2006 to Polish AF.
The main differences between both are:
1.Addition of support for conformal fuel tanks (CFTs), which provide an additional 440 US gallon or approximately 3,000 pounds (1,400 kg) of additional fuel, allowing increased range or time on station and frees up hardpoints for weapons instead of underwing fuel tanks.
2.A dorsal spine compartment. All two-seat (D-Variant ) “Plus” aircraft have the enlarged avionics dorsal spine compartment which is located behind the cockpit and extends to the tail. It adds 30 cu ft (850 L) to the airframe for more avionics with only small increases in weight and drag
3.The APG-68(V9) radar.
4.an On-Board Oxygen Generation (OBOGS) system.
5.a JHMCS helmet, which gives a lethal edge in WVR combat.