Yesterday one of my professional baseball clients and I were discussing his tight hips. The conversation stemmed from mobility drills being more difficult and taxing than any other part of his workout.
He said that he'd always been instructed to "get more flexible," but he never understood what that meant or how to achieve that.
I explained to him that there is a big difference between flexibility and mobility. And focusing on improving mobility would be more beneficial to him as an athlete.
Mobility represents much more than merely flexibility that you can identify in such things as a sit and reach test, or the ability to touch your toes. Mobility is how multiple body segments (hips, pelvis, trunk, ankles) interact in functional situations.
Flexibility is the ability to gain ideal extensibility of the appropriate tissues in the right range of motion.
Grey Cook says, "mobility represents muscular flexibility, joint range of motion, and multi-segmental interaction of body parts in functional positions and movement patterns ."
So in essence, flexibility is focused on a single joint range of motion, and it's ability to extend its tissues, mobility focuses on the interaction of and range of motion of multiple joints working together.
You can be flexible and immobile. And, you can be inflexible and mobile. They are two completely different things.
Understand that both are important, but flexibility without motor control and strength is useless.