Hong Kong Airlines typically offers Business and Economy cabins (with First or Premium Economy on some widebody/long-haul routes). Cabins differ notably in seating, catering, baggage allowance and mileage accrual.
For short routes economy is usually the best value; on overnight or long-haul flights Business meaningfully improves rest. Watch for upgrade offers with miles or cash around check-in time.
Product-wise: Hong Kong Airlines focuses on regional full-service routes from HKG to the mainland, Japan/Korea and Southeast Asia, typically undercutting Cathay on price — a value option through Hong Kong.
On loyalty: Fortune Wings Club members accrue miles by cabin, and elite tiers add seat, baggage and lounge benefits — worth joining if you fly Hong Kong Airlines often.