What are the key differences between oil type transformer vs dry type transformer?

Oil type transformers use liquid insulation for cooling and dielectric strength, enabling higher ratings and compact design, but require oil management and spill protection. Dry type transformers use air and solid insulation, reducing fire and environmental risks, but are larger and limited in rating. Oil types dominate transmission and outdoor substations, while dry types are common indoors and commercial buildings. The choice affects safety, cost, footprint, and maintenance strategy.