Let tens place digit be y and the units place be x.

∴ Our number is (10y + x)

Our given first condition is that the difference between a 2-digit number and the number obtained by interchanging its digits is 63.

∴ By given condition,

(10y + x) - (10x + y) = 63
∴ 10y - y + x - 10 x = 63
9y – 9x = 63
9(y - x) = 63
y - x = 7

Hence, the difference between the digits of the number is 7.