On resistors with four colour bands, which colour band differentiates two resistors rated at 33 ohms and 39 ohms respectively?

In the standard four-band resistor colour code, the first two bands represent the first and second significant digits of the resistance value. For a 33-ohm resistor, the significant digits are 3 and 3. For a 39-ohm resistor, the digits are 3 and 9. Because the first digit is a '3' for both resistors, their first colour band will be identical (Orange). However, the second digit changes from '3' to '9'. Therefore, the second band differentiates them (Orange vs. White). The third band is the multiplier. Since both 33 and 39 require no extra zeros, the multiplier band (Black) will be the same for both.