A goal without a plan is just a lofty idea that circulates our brains but we never really do anything about. A plan without a goal may give us something to do, but without a concrete idea of what the end result ought to be, ultimately causes us to do a lot of work - or the wrong kind of work, or not enough work - for nothing.
If you are dead-set on a specific result (and this is not just pertaining to fitness), then you need a goal-based plan. That is, you will focus all of your efforts and hone your skills and work with unrelenting perseverance. This is what most people who come into my gym set out to do. "I am going to lose 50 pounds in 6 months!" someone may say. Is that doable? Absolutely. But if that person embarks on a goal-based plan she is going to have a LOT of work ahead. If The Goal is addressed as the primary concern and The Plan is secondary, you run into a situation that I see happen in the gyms every year, right around January: Everyone comes in all gung-ho, Instagram feeds are clogged with #fitspo posts and treadmills are clogged with people taking selfies. Cut to a couple months later when the gym is empty as 75% of those people realized they really can't work out e.v.e.r.y. day. Their efforts becomes shorter and less focused, and the determination withers.
Plan-based Goals, however, require a different approach. They require one to look at his or her schedule, consider all barriers that may prevent a consistent routine, take stock of all previous excuses, and carefully and methodically eliminate each roadblock on by one. The Goal is a little less specific, such as to simply "lose weight" or "gain strength," but can become more focused over time as the plan unfolds. A Plan-based Goal takes longer, too, as it is more about developing the habits that contribute to a lasting lifestyle change rather than just changing ones' dress size. It's about keeping a constant and consistent forward momentum - not flooring it and then crashing in a matter of weeks.