Simple:
Logbook flying hours are Chocks off to Chocks on. This is, I believe UK CAA standard. Max 900 hrs per year and 100 per 28 days.
The Flight duty as per required to compare with max Flight Duty Period is report (1 hour before Scheduled departure) untill chocks on for last flight, again CAA regulated.
Duty time is report until clear - standard clear for pilots is 30 mins after chocks on.
This is for one of the UK Charter carriers.
hope this helps.