What's the difference?

It shouldn't affect (not "effect") the meaning in that example.

"Much more" is far more common!

Thank you for both answers, if I may trouble you with another small question:

When we meet that special person, how can we tell that our feelings are genuine and not merely infatuation?

Can we use ''whenever'' instead of ''when in the above question?
Thank you.

You should ask new questions in a new topic, because that way you can select an answer and mark this one "answered".

But here's your answer anyway: yes you can, but "whenever" can be misunderstood to mean something more frequent. e.g.

Whenever I get tired I sleep.

No you shouldn't use "whenever" there, because the meeting of "that special person" is a once-only event (since you use the phrase "that special person": so that's one person only, and the meeting logically is only one event)

There is no difference in meaning.

Thank you all for taking time to reply, I appreciated.

English is not my first language but still I can draw your kind attention to peruse this link to enrich your English
http://www.worldwidewords.org/index.htm