[winbig]

5+1 has higher chance of winning, that's why the prize is lower. Can do a simple calculations:

1. Strike all 6:

P1 = 1/c(49, 6)

2. Strike 5 + 1:

P2 = c(6, 5)×c(43, 1)/c(49, 6)

Look up for
c(6, 5)×c(43, 1) = 6x43 = 258

So p2 = 258 x p1

5+1 is also 6 numbers. Probability to get 6 numbers are the same.