Does this mean you get an error?

depends upon the code.

if I were to write:

dim ws as worksheet
set ws = sheets(1)

Yes, it would error.

You can use the error condition to locate the Oracle sheet.

I could.

do you get the same number of sheets using sheets and
worksheets?

No. worksheets.count = 29 ; sheets.count = 30

I saw something a while back about the distinction between a "Worksheet" and
a "Sheet"