The bottom picture use to be one of the most popular bowling balls on the market before the day of resin bowling balls. The urethane bowling ball is a lot different than resin. They are both needed in today’s day and age because of different oil patterns. Urethane balls are a little softer and tend to hook a lot sooner than resin balls. Resin bowling balls tend to store more energy and hook a lot more.
Urethane balls work really well when the oil pattern is shorter and lighter volume. The reason you would use this kind of ball is because they will start early and they will be really smooth. If you use a reactive resin ball you will tend to get a lot more violent reaction. Very few people can use urethane on all patterns but when they do it is very risky.
Reactive resin will be good on just about everything and they will be longer and more angular than urethane. You can do a lot of different drilling’s on a resin ball and can make it do a lot of different things. The urethane ball is very one dimensional and it is very hard to make the ball do anything different. Urethane balls use to dominate the scene back in the day but nowadays reactive balls are taking over the market and will continue to dominate the game today.