What's the difference between Nokian's summer and winter tires?

As someone who has owned multiple sets of Nokian tires, I've often wondered what exactly differentiates their summer and winter tires. On one hand, summer tires seem to offer incredible grip and handling on dry roads, but become too soft and prone to wear in cold temperatures. Winter tires, on the other hand, are designed specifically for snowy and icy conditions, with special tread compounds that remain pliable even at sub-zero temps. However, I've heard they can be noisy and compromise some of that summer tire performance. What's the actual difference between these two lines?