Which of these sentences is correct:
- Pain tolerance differs from person to person
- Pain tolerance differs between person to person.
Why is one preferred over the other?
When someone says “person to person” they’re implying general and ongoing links within a larger group. Like “The virus spread from person to person” suggests that it’s moving among a larger group, not just two individuals, though you could specify two individuals, like “The virus spread from Dave to Janet”.
When you use “between” you need to either specify two individuals as above, or you need to use a collective term like “Pain tolerance differs between [different] people”.
So your second example would be considered incorrect, but if corrected I don’t think there’d be much preference between the two forms.