Use 'not to say' to emphasize how the next term stands out in comparison to the first.

Stress Contrast

The phrase helps depict a rising scale or intensity of a characteristic.

Escalating Ideas

It's a polite way to suggest an alternative, perhaps more accurate or extreme, term.

Use it to indicate someone's or something's limit in a stark, clear-cut way.

Serves to dismiss more extreme cases after mentioning a barely attainable scenario.

Expresses the difference between feasible and less feasible abilities.