Caller information display feature
When you receive call from someone, sometimes you want to know what the person has been up to lately or about what and when the conversation was made between you and the person. With the Galaxy Note 4, you can check information about the relevant information about the person when you are receiving a call from, or making a call to, or even during a call.
#Samsung

Tilt for a Customized Playlist
Tilt the Galaxy S5 horizontally (into landscape) while listening to a song via music player, and your Galaxy S5 instantly suggests similar tracks among the songs stored on your phone based on information of the current song, such as its genre, mood, source, etc. So the more songs you have, better the recommendation
#Samsung

Virtual Tour
feature that allows you to take pictures as if you are giving a tour of the surrounding area to viewers.
#Samsung

Merged functionality of 2 button navigation with 3 button navigation (Only available in android 9 OneUI)
#Samsung

Built-in 360° camera
#Protruly

Erase data without internal storage
#OnePlus

Speaker ONLY inside USB C hole
#Huawei

Dual display
Cameras are only on one side so you can enjoy notchless display.
#Vivo

Glove mode
#Sony

Meizu had a unique home button called "mBack" that combined touch gestures and physical presses for navigation. A light tap would go back, and a full press would go home.
#Meizu

"Light-up notifications"
RGB LED back on Alcatel A5 LED
#Alcatel

Nokia OZO Audio
This technology provided 360-degree spatial audio recording and playback.
(OnePlus 8 on the picture with OZO audio)
#Nokia

Variable Aperture
#Samsung

Privacy shade
Only show a small area of the screen for privacy.
#Blackberry

Screen SoundCasting
Technology that turns the entire screen into a speaker, enhancing audio output without traditional speaker grills.
#Vivo

Flexible shape
#LG

Smart cover
#LG