I want to pass a named range (e.g.- alookup which names cells A21:A46)
to the 1st argument in VLookup(lookup_value, ....).

I know I am able to pass a named range (e.g.- Adata which names cells
$A$19:$H$40) to the 2nd argument in VLookup(..,table_array...).

Basically, I want to see the difference in values between identical cells
from 2 different wksheets within the same workbook. The formula looks
something like this:
=VLOOKUP($A5,$A$3:$H$24,2,FALSE)-VLOOKUP(ExampleSheet1!$A21,INDIRECT("'["&$A$50&".xls]"&$A$51&"'!"&$A$53),2,FALSE)

This would solicit from the user the following:
Cell a50-enter workbook name (the excel file with extension .xls)
Cell a51-worksheet name
Cell a53-table_array name

The result will be the difference.