1820 large cent small v large date

Pacoin

Per usacoinbook online, a curl 2 is the characteristic for a small date, a knob 2 for a large date. Ie two types of obverse.
Per bowers guide book, the determining characteristic is the '0', and both large and small date has both types of '2'. Ie four types of obverse.
Can anyone shed light on this?
Ignore for now the 1820/19.

lermish

From coinfacts:

Pacoin

That matches what I found on usacoinbook. Here are the excerpts from bowers guide

lkeigwin

For the non-overdates, if the 2 has a curly top it is a small date, except for the N.9 die pair.

If the 2 has a knob or club top it is a large date.

The 3 overdate die pairs all have curly tops. The N.1 is a large date, the N.2 and N.3 are small dates.
Lance.

Edit to add, Noyes disagrees with what is in the Bowers guide re the N.14 and N.15. The N.14 is a knob 2 large date. The N.15 is a curl 2 small date.

Pacoin

Thanks