The motor with 4 poles has a tendency to generate more torque compared to 2 poles same volume and kv rating one. That means for same rpm it can generate more power output since the power = torque x rpm. 4 pole motors generally used in 8th scale buggy and truggy due to their weights. However, with the existence of high weight ( around 7lbs) 4wd short course trucks with 2s lipo, they become popular in last 3 or 4 years.