What does WithAndAsDefaultOperator() do?

I have used QueryStringQuery.DefaultOperator to change the default operator of the query. My intention is to make the search operator 'AND' instead of 'OR'.

IClient client = SearchClient.Instance;
client.Search<SearchType>().For(Query, q=> {
                    q.DefaultOperator = BooleanOperator.And;
                }).Take(1000).GetResult();

And also I have got to know that the WithAndAsDefaultOperator() does the same thing as above ('AND' search instead of 'OR').

IClient client = SearchClient.Instance;
client.Search<SearchType>().For(Query).WithAndAsDefaultOperator().Take(1000).GetResult();

Are these two search implementations do the same thing without any difference in the resultset?

Note: I did not find the WithAndAsDefaultOperator() in the Episerver Find Documentration. It's better if anyone could share the link of that just to refer.

Thanks.