create one view to control tables or columns

I have 2 instances oracle 'MYDB' and 'DBX' with table's owner 'TOM'

I'd like to control all the tables and all the columns in order to verify that they are equal in both instances.

I tried this query on a single instance:

select owner, table_name, column_name, data_type, data_length, data_precision, nullable, data_default
from dba_tab_columns
where owner='TOM'
order by table_name

I get more 4000 records.

but in order to control all the tables in this way are much laborious one.

Can I create one view o query on both instance to control the table (or col) differences?

Must I create a dblink?

Thanks in advance!

See attachement