What is the difference between A50 &M30 (6GB RAM)?
Bro M30 can be compared to A30, not A50. A50 is upper ranger. If in future M50 comes then that will be par with A50.
Security:
A50 has in-display fingerprint sensor which is only second phone to get after their flagship Galaxy S10 series.
M30 has traditional rear fingerprint.
Software:
A50 (including A10 & A30) comes with Samsung's new One UI which is based on Android 9 Pie.
M30 has Samsung Experience v9.5 UI which is based on Android 8.1 Oreo
Battery capacity:
Battery of M30 is 5000mAh where as A50 has 4000mAh.
Both mobile supports fast charging.
Camera:
A50 rear camera: 25-megapixel + 5-megapixel + 8-megapixel
M30 rear camera: 13-megapixel + 5-megapixel + 5-megapixel
A50 front camera: 25-megapixel (f/2.0)
M30 rear camera: 16-megapixel (f/2.0)
Processor:
A50 has newer and better Exynos 9610 processor
M30 has Exynos 7904 processor
I have collected information available on various sites and compare these two phones for you. Hope it helps.