SQL Server 2012 :: Reconcile Values In 2 Databases

I am trying to reconcile two different databases. Each database holds customer information and some of this information is represented as drop down tables. Here is how it is linked

Structure

Tables Fields

Attribute names Name, AttID, AttValue
Attribute Values AttID, AttValue, CustID, CustCode
Customer DBID, DBCode,CustID, CustCode, FName, LName

Database 1 Sample

Attribute name Attribute Values Customer
Color 8, 0 8, 1, 1234, 6 892, 14, 1234, 6, John, Doe
red 8, 1 8, 2, 1234, 6
blue 8,2

Database 2 Sample

Attribute name Attribute Values Customer
Color 5, 0 5, 3, 1234, 6 892, 14, 7434, 5, John, Doe
red 5, 3 5, 4, 1234, 6
blue 5,4

Within a database, the ATTID and Attcode link the attribute and attribute value tables and they link to the Customer table with CustID and Cust Code. One Customer may have multiple entries within the Attribute value table

The Customer tables in each database are linked by the DBID and DBCode values. The other ID's are not necessarily the same across databases.

The object is to compile a list of Customers where these attribute values vary between databases. There are approximately 56,000 Customers in the customer table and 710,000 entries in the attribute values table.

My attempts to do this have produced cross joins with millions of values returned