May I assume that you "updated files" are loaded into *separate* tables in the Access DB?
And may I assume that you have some way of knowing which records in the existing table correspond to which records in the new table (e.g, some sort of unique identifier)?
If so, it's not hard, but it's quite tedious.
You will need to do something like this:
FROM oldTable AS T1, newTable AS T2
WHERE T1.id = T2.id
AND ( T1.field1 <> T2.field1
OR T1.field2 <> T2.field2
OR T1.field3 <> T2.field3
OR T1.field150 <> T2.field150 )
That code assumes that the "id" field is the one unique field (could be a combination of fields) that "connects" the two tables.
This will give you a list of the the id's of all the records that are not the same. Now, finding in what WAY the pairs of records are not the same is much more tedious, and pretty much has to be done on a per-field basis. It's a job that is better done in VBA or some program external to Access.