Raytheon 4000 / Hawker Beechcraft Hawker 4000
Hawker Beechcraft’s top model, originally developed by Raytheon Aircraft as the Hawker Horizon, is loosely based on the BAe125, but actually only the forward fuselage including the cockpit looks familiar: especially the large curved cockpit front windows are similar to those of the Hawker 800 to 1000 series. There are no really clear recognition points, but the Hawker 4000 has no winglets and the engine nacelles have clearly visible fairings for the thrust reversers, typical for the PW300 series engines.
Confusion possible with
These are the best ways to distinguish the G280 from the Hawker 4000: the G280 has winglets, no fairings for the thrust reversers and more cabin windows. But is you know what to look for there are more differences in the details.
Another close call may be with the Embraer Legacy 450/500 and Praetor 500/600. For recognition again look closely at the cockpit windows, dorsal fin and the presence of winglets (Embraers) and fairings for thrust reversers (Hawker 4000).
Like the similar aircraft above Citation Longitude has different cockpit windows, winglets and no fairings for thrust reversers to allow recognition from the Hawker 4000.
Being derived from the British Aerospace 125 you might mix them up, especially the Hawker 1000 version pictured here. The Hawker 1000 has six cockpit windows though and a cruciform tail instead of a T-tail.