A straight is harder to hit then a flush. I know, it goes against the rules of poker, but look at it this way. Let's say you have 4 cards to a flush and you're chasing it. There are 13 of a suit and 4 of them are on the table / in your hand. That leaves 9 cards you're chasing. Now look at an outside straight. You have 4 cards in a row, that means you need the card before or the card after your streak. That's 2 possible numbers, multiply that by 4 suits and you've got 8 cards you're chasing. If you're chasing an inside straight, you're down to 4 cards.

So a flush draw has 9 outs, an outside straight has 8 outs, and an inside straight has 4 outs. If you're chasing a straight, and they're chasing a flush, they have better

odds of hitting their flush even though a straight is technically a weaker hand. Statistically, the Flush Draw (9 outs) is easier to hit than the Straight draw (8 or 4 outs).