Cast iron is another material to consider because it retains heat extremely well, although it's not the best heat conductor. That means, cast iron takes a while to heat up. Cast iron is best for searing, sauteing, and baking.
When it comes to size, both the frypan and skillet are available in various sizes. What sets them apart is the range of sizes offered. The size of frypans usually range from 15cm to 30cm, with the most popular sizes being between 24cm and 26cm.