Waco ATO / CTO Taperwing (multiple)

I photographed this Waco ATO at the Waco Museum in Troy, Mich. On the museum signage, the plane is labeled as a Model CTO Mackey Taperwing… but it is registered as an ATO and I am not sure if there is any visual difference between the ATO and CTO variants.

1929 Waco ATO #A-118

Waco Museum 2018

1928 Waco ATO #A-20

WAAAM, Hood River 2021

1929 Waco CTO #AT-3005

WAAAM, Hood River 2021