The length of one segment is 10cm, the length of the other is 6cm, how much one segment is longer than the other.

The problem can be solved in two ways.

Build a segment, let’s call it AB = 10 cm and on it a segment AC = 6cm. You can measure the length of the segment CB, because that is exactly how much the segment AB is longer than the segment AC. CB = AB – AC = 10 cm – 6 cm = 4 cm.
You can use the rule: to find out how much one number is greater or less than another, you need to subtract the smaller from the larger number.
10 – 6 = 4 (cm) by so much the length of one segment is greater than the length of the other segment.

Answer: one segment is 4 centimeters longer than the other.