>>

>>declare @x char(20)
>>set @x = 'test%'
>>select @x + '<'
>>
>>declare @y varchar(20)
>>set @y = 'test%'
>>select @y + '<'
>>

>>
>>there's a big difference between those two as far as the LIKE operation is concerned
>
>I am not sure I understand your examples here.

These two things are not equivalent as a LIKE clause

test%               <
test%<

The trailing spaces are significant between the char() and the varchar() variables.