Differences between match and search in python regular expressions

In Python, you try to find if the string contains "a something:" as a regular expression.

import re
re.match(r'a[\s\w]+:',"a something:")#a preceded by a space

This will result in None.

import re
re.search (r'a[\s\w]+:',"a something:")

If I do it, the results come out well. I know that there is a difference in the number of matches and search. Is there a difference in the search method?