Sony A9 II advantages over Nikon D5100

• Focus peaking
  Peaker vs Non-peaker
  Your camera will highlight what's in focus
• Larger sensor
  35mm vs APS-C
  More sensor area. Bigger is (generally) better.
• In-Camera Image Stabilization
  Yes vs No
  Reduces the effects of camera shake at slower shutter speeds
• Bigger pixels
  ~ 5.93 vs 4.79 microns
  Better low-light and dynamic range (all else equal)
• Shoot 4K video
  4K (UHD) vs 1080p
  Make sure you have a fast computer
• Touchscreen
  Touch vs No touch
  Interact with your camera just like your smartphone
• Built-in Wi-Fi
  Wi-Fi vs None
  Share your photos wirelessly
• NFC
  Yes vs No
  Simplifies pairing your camera with supported phones
• Built-in Bluetooth
  Yes vs No
  Always-on wireless connectivity
• On-sensor phase detect
  Yes vs No
  Usually improves live view and video AF performance
• Newer
  5 years vs 14 years old
  Newer cameras often support more advanced features
• More dots on screen
  1440k vs 922k dots
  Can mean greater resolution or a brighter screen
• More viewfinder magnification
  0.78x vs 0.52x
  Get a bigger view of the scene through the eye-level viewfinder
• More pixels
  24.2 vs 16.2 megapixels
  Higher resolution photos
• Shoots 60p video
  Yes vs No
  A faster framerate can give you more editing options
• Dual card slots
  Yes vs No
  Gives you more storage flexibility
• Headphone jack
  Yes vs No
  Monitor audio recording while you shoot video
• Faster JPEG shooting
  20.0 fps vs 3.9 fps
  Faster JPEG shooting (burst mode)
• Bigger JPEG buffer
  361 vs 100 shots
  Take more JPEG shots before waiting (burst mode)
• Faster RAW shooting
  20.0 fps vs 4.0 fps
  Faster RAW shooting in burst mode
• Bigger RAW buffer
  239 vs 13 shots
  Larger buffer for RAW shots (burst mode)
• Slow-motion videos
  Yes vs No
  Shoot slow-motion videos
• Faster shutter
  1/32000 vs 1/4000 sec
  Shoot wide open in bright light
• Higher extended ISO
  204800 vs 25600 ISO
  Higher extended ISO can give more low-light flexibility