CHAR LIKE VARCHAR

Hi!

I came across following difference
between "LIKE" and "=" regarding
CHARs and VARCHARs

create table aa(f5 char(5), fv varchar(5));
insert into aa values('str1', 'str1');
select count(*) from aa where f5 = fv;
> 1
select count(*) from aa where f5 like fv;
> 0

I understand trailing spaces in CHAR are not
significant though I expect DBMS shows
consistent (and, ideally, clearly documented)
behavior. 

From my point of view in example above 
it would be nice to have the same result 
for both queries regardless it is 0 or 1.

Of course, I may be wrong. Is there a clear 
concept behind the difference between "LIKE"
and "="?

Thanks.

-- 
Best regards
Ilja Golshtein