join condition against where with coalesce

Should there be any difference between:

select * from table1 a left join table2 b on a.pk=b.fk and b.typeid=14
and
select * from table1 a left join table2 b on a.pk=b.fk
where coalesce(b.typeid,14)=14

The reason I need to use the coalesce is because my goal is to do it with a full join and can't use
the and condition because it is not merge-joinable.

My test with the left join showed me that with the where it doesn't give any results, while I would
expect it to give me all the results in the first table.

Any thoughts?