Detailed answer
Progress describes completion of a task; meter describes a scalar measurement within a known range.
Give either one a useful label and accurate values. Progress without value represents indeterminate progress. Do not show invented completion merely to suggest activity, and avoid meter for a task that is still running.
Example
<label for="upload">Upload progress</label><progress id="upload" value="30" max="100">30%</progress>
<label for="score">Quiz score</label><meter id="score" min="0" max="10" value="8">8 of 10</meter>
Understanding the behavior
Progress describes completion of a task, while meter describes a scalar measurement within a known range. Their value and limit attributes need to reflect the real quantity. A decorative percentage without context is difficult to interpret.
Practical implementation notes
For progress without a known total, omit value to express an indeterminate task. For a measurement, label the units and range so a value such as 70 is not mistaken for 70 percent completed.
How to check it
Check the intended meaning, label, range, and current value for each element.
Expected result
Progress describes a running task; meter describes a bounded measurement.
Watch out: Task completion and a measurement within a range are different concepts.
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