The launch Date of the first phone is February, 2019. The cost of Samsung Galaxy A50 is Rs. 19990. The launch Date of the second phone is February, 2019. The cost of Samsung Galaxy M30 (6GB RAM + 128GB) is Rs. 17990.
Samsung Galaxy M30 (6GB RAM + 128GB)'s larger 6 GB RAM is better for playing games and all with respect to Samsung Galaxy A50's lower 4 GB RAM. Samsung Galaxy M30 (6GB RAM + 128GB) has more Internal Memory (128 GB) than Samsung Galaxy A50 (64 GB). Both of the devices have Memory Card Slot.
Samsung Galaxy A50 has better rear camera Resolution of 25 MP to Samsung Galaxy M30 (6GB RAM + 128GB)'s camera resolution of 25 MP. Samsung Galaxy A50 will be better choice if you're looking to click lot of selfies as it has better Front camera resolution of 25 MP in comparision to Samsung Galaxy M30 (6GB RAM + 128GB)'s camera resolution of 16 MP.