Real ext hdd when you access file, you can feel slight vibration due to the moving actuator and motor, or can put close to your ear, real hdd have tickling noise, fake hdd use reprogrammed flash chip thus have no noise.

exFAT if you becareful , corruption is hardly problem if you mostly read files, corruptions occurs if you write files and there's sudden disconnection.
My ext HDD also formatted to exFAT for my android phone usage.