Tribal rugs and City rugs
Basically there are two types of rugs in Iran. City rugs and Tribal rugs.
City rugs are more formal in design and woven with Persian knots that can be easily counted.
Tribal rugs are made in Tribes or villages. They are more casual and geometric in design and woven with Turkish knots. Unlike Persian knots, Turkish knots are not counted since woven entirely with a different technique. Tribal rugs are considered to be very durable and made for heavy traffic areas.

Persian knot

   Persian knot
   Persian knots match asymmetrically around a pair of warp, one string loops around a warp entirely and the second one only a half loop. Other names of knots of this type are: senneh knot named after the Persian city of Senneh (now Sanandadje in the Iranian Kurdistan) and asymmetric knot.

Turkish knot

   Turkish knot
   Turkish knots symmetrically match around a pair of warp. Both strings are completely twisted with a nap yarn.  Despite of the specified names, both types of knots have no precise national binding. Both are used in Iran, and in Turkey.