Resolution: I resolve to drink more water. Vague. No tangible measurement of success.
Plan: I have a beverage container of known volume. I will drink four of those full of water a day to equal my 8x8 - eight glasses of eight ounces. Solid. Success can easily be measured.
Resolution: I will get back into a regular writing routine. What is "regular"? How is that measured?
Plan: My calendar lists projects and deadlines. Some have detailed goals of how many words must be completed by which date. Success is defined. Goals can be quantified. Work time is recorded.
When you have contracts and deadlines, it's easy to measure writing success. With other fiction projects, your goals may be more difficult to define. It's helpful to set word or page goals - how many a week. Or completion goals - rough draft of a short story by the end of February.
Sometimes things happen that are out of our control. That is where a plan makes itself useful. If you are bumped off track by life events, you can consult your plan when things settle back to normal. Or some version of normal.
We're nearly halfway through January. Resolutions may be falling by the wayside as I speak. But plans endure. Stick to it, and you'll make progress toward your 2023 goals.