Embraer 505 Phenom 300 & Phenom 300E
The second smallest Embraer corporate jet is clearly a sibling of the smaller Phenom 100. Both share a lot of components. The Phenom 300 is longer though, with five cabin windows on the left and six on the right side. The wings are swept with winglets straight up from the tips. Another notable feature is the tail: the horizontal stabiliser appears to be tilted to the front. This characteristic is also present on the larger Legacy/Praetor models and makes it easy to recognise an Embraer jet. The EMB505 has a single step dorsal fin.
There are two versions, which are externally the same. The Phenom 300 is the baseline version. The Phenom 300E only has a redesigned cabin.
Confusion possible with
Embraer 500 Phenom 100
You are very likely to mix-up the Phenom 100 and Phenom 300, although the Phenom 100 is smaller with four cabin windows, has straight wings, and the Phenom 300 swept wings with winglets. Still they have a lot of in common externally.
Cessna 650 Citation III
The main differences between the Citation III and the Embraer Phenom 300 are in the cockpit windows (the Cessna has six), engine nacelles with thrust reverser fairings and top of vertical stabiliser. Also note that the Phenom has both a dorsal fin and a ventral fin, as well as winglets. FInally, the Citation has double wheel main gears.
Learjet family
Many of the Learjet family could be potentially mixed up with the Phenom 300, especially the ones with winglets like the Learjet 28/29, 31 and 40/45. All Learjets have double wheels on the main gear. Other models are bigger (Learjet 55/60) or have tip tanks, making confusion less likely.
Pilatus PC-24
Another look-a-like of the Phenom 300 is the Pilatus PC-24. The differences compared to the Phenom are in the details, mainly the double wheel main gears, cockpit windows, tail and (lack of) winglets.