SQL Select comparing two tables with different orientations

How can I join two tables with different orientations?  Table A lists each attributeID horizontally.  Table B below lists each attributeID vertically.  I need to find  all the attributeID's from TABLE A that  have a value and category not listed in TABLE B.
There are 400 attribute ID's.  

Table A (Products)
A_100      A_200       A_300     Category
   S               C                B           WebFolder1
   S               C                B           WebFolder2

Notice how A_300 has value of "B" for WebFolder1.   A_300 and Webfolder1 do not exist in Table B and this is what I need this SQL to do.  Find attribute to category discrepancies between table A and B.

Table  B  (Configuration)
AttributeID      WebFolder
----------------       ------------
A_100              WebFolder1
A_200              WebFolder1
A_100              WebFolder2
A_200              WebFolder2
A_300              WebFolder2

Expected Result:
AttributeID   WebFolder
    A_300         WebFolder1
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ste5anSenior DeveloperCommented:
Dig into your data model. Does a normalized version of your data exists? Means is this a view or really a table?

When it is a table, then you need to normalized it by using UNPIVOT. E.g.

SELECT  Category,
FROM    TableA
UNPIVOT (   AttributeValue
            FOR AttributeType IN ( A_100, A_200, A_300)) U;

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Use the result set either as CTE or materialized table to use FULL JOIN or INTERSECT/EXCEPT for comparision of both sets.

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