Oil Filter differences - Audi pn's?

[Dave Conner <conner@cfm.ohio-state.edu>]

I have been using filters with pn 056 115 561G in these 5 cyl Audis...86
4kq, 87 5ks, and 89 100, so I buy them in quantity.  I thought this would
be the same one to use on the 91 200tq, but now I learn the correct one for
this car has a different pn...034 115 561A.
Can anyone tell me the difference between these two filters aside from the
561A costing about twice as much?

I looked at a FRAM filter catalog and it shows the same one is used in all
these cars.  I know FRAM isn't the best filter, but this is a bit confusing. 
Dave Conner
Columbus, OH 
87 5KS
89 100E
86 4KCSQ
91 200Q Avant