They're often used synonymously, but capability and capacity are two very different things. Jason Day, for example, has the capability to hit 330-yard drives. His capacity to unleash a bomb on a given tee box, however, is limited, given external factors that affect on-course performance—an aching back, wind, a swing that's just "off" that day. Elite golfers understand that it's rare to be firing on all cylinders. Usually, they operate at about 80 percent of max capability (if Day has 40 shots in his short-game arsenal, he realistically can pull off about 32 in tourney conditions).
What makes it look like they're humming along is their focus on what they have, not on what's missing. You? Weekend players tend to fight this discrepancy, attempting shots and swings that live in the gap between what's possible and what's possible right now. You attempt Mickelson-style flops because you pulled one off two seasons ago. You try to carry a fairway bunker because you used to drive it 250 yards. Playing "capable golf" instead of "capacity golf" is costing you strokes.
My advice: Compete with the swing you brought to the course, not the swing you dream about. If you're catching shots off the toe, so be it—adjust your aim to accommodate the toe strike, and pull an extra club to cover the loss in distance. Save the swing fixes for your next practice session. It's the rare golfer who can tinker and win at the same time.