The Samsung Galaxy A31 will launch in India two days from now (on June 4) and it will be exclusive to Flipkart. For now, there retailers teaser page holds only a Notify me button along with some spec highlights.
The price is expected to be around INR 23,000 (but that hasnt been officially confirmed). This will be quite a premium over the Galaxy M31, which started at INR 15,000 (though lately you can only find the 6/64GB version for INR 16,000). The two phones have some things in common, like the 6.4 1080p+ Super AMOLED display. However, the A31 has an in-display fingerprint reader while the M31 has a traditional rear-mounted reader.
Samsung Galaxy A31 in Prism Crush Black, Prism Crush Blue, Prism Crush Red and Prism Crush White
Both phones have quad cameras with similar make-up: wide, ultrawide, macro and depth. However, the M31 has a 64MP main sensor capable of 4K video capture, the A31 has a 48MP 1080p camera. The M31 also has a larger battery, 6,000mAh vs. 5,000mAh, but the A31 is slightly more compact and lighter.
Anyway, the price difference may be due to a different configuration, i.e. we may only see the 6/128GB version of the Galaxy A31 (but going from 64GB to 128GB is usually an INR 1,000 upgrade).