Galaxy A51 vs Galaxy M31: Which Should You Buy?

The Galaxy M31 is Samsung’s new mid-range smartphone with a 6,000 mAh battery. It has similarities with other models that go beyond the name, such as the Galaxy A51, available since January. Both have a quad-camera and a large screen. Besides, the prices are not so different: the Galaxy M31 is currently sold for $355. The Galaxy A51 is currently sold on an e-commerce store for $324. See below the differences in the technical sheet.

Galaxy A51 and Galaxy M31 Datasheet

Galaxy A51Galaxy M31
LaunchJanuary 2020July 2020
Current price$324$355
Screen6.5 inches6.4 inches
Screen resolutionFull HD + (2400 x 1080 pixels)Full HD + (2400 x 1080 pixels)
Processorocta-core up to 2.3 GHzocta-core up to 2.3 GHz
Storage128 GB128 GB
Memory cardyes, microSDyes, microSD
Main cameraQuad camera: 48, 12, 5, and 5 megapixelsQuad camera: 64, 8, 5, and 5 megapixels
Front Camera32 megapixels32 megapixels
Battery4,000 mAh6,000 mAh
Operating systemAndroid 10Android 10
Dimensions and weight158.5 x 73.6 x 7.9 mm; 172 g159.2 x 75.1 x 8.9 mm; 191 g
Available colorsblue, black, and whiteblue, black, and pink
Source: Samsung

Screen and Design

Galaxy A51
Galaxy A51

Both phones feature a Super AMOLED screen with Full HD+ resolution, but with a small difference in size and look. While the Galaxy M31 features a 6.4-inch notch-shaped display at the top, the Galaxy A51 features a camera inside the 6.5-inch panel.

The Galaxy M31, by bringing a bigger battery, ends up being thicker and heavier. Also, the A51 features a more modern design, as the selfies sensor is in a more discreet position.

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Other appearance details are very similar, including the rear camera organization and the materials, with a plastic finish. In terms of color, the Galaxy A51 is available in blue, black, and white. The Galaxy M31 is available in blue, black, and pink.

They also have standard headphone input and have no advanced resistance to water and dust.



A quadruple camera system is present in both models, with two differences. The most important is the main sensor, which in Galaxy A51 has 48 MP and an f/2.0 aperture lens. The M31 has a more powerful 64 MP primary camera with an f/1.8 aperture that tends to capture more light from the environment. As a result, the M31 tends to deliver more detailed photos, especially when the environment does not have good natural light.

On the other hand, the Galaxy A51 should produce better photos with an ultra-wide lens, which has a 12 MP sensor against only 8 MP in the M31. Moreover, the mobile phones match in terms of the photographic specification: a 5 MP macro camera to capture objects from close range, plus a 5 MP depth sensor to perform the famous portrait mode.

The front camera is also the same, with 32 MP. However, the M31 has a slightly larger lens aperture that can deliver brighter selfies.

Performance and Storage

Samsung Galaxy M31

The Galaxy M31 has 6 GB of RAM and therefore tends to be faster in everyday life. With only 4 GB, the Galaxy A51 can have more difficulties when dealing with several open applications at the same time. On the other hand, the performance in games and heavier programs shouldn’t be so different, since the processor is the same, Exynos 9611 (octa-core up to 2.3 GHz).

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In terms of storage, the specifications match again. Both have 128 GB internal memory, of which about 108 GB is free for use. They also support expansion via microSD cards.


The size of the battery is the main attraction of the Galaxy M31. With 6,000 mAh of capacity, it’s bigger than most cell phones sold at similar prices, which also includes the Galaxy A51, which has 4,000 mAh. According to Samsung, the difference translates into up to six hours more navigation with 4G on the M31.

Android Version

Galaxy A51 and M31 run Android 10, the latest version of the system. The user experience, therefore, tends to be the same, as they bring the same design as the One UI 2.0 interface and have the same factory-installed apps. It is not yet known if mobile phones will receive Android 11, which is already in the Beta version.

Additional features

The Galaxy A51 loses performance and battery but brings some features missing in the Galaxy M31. One of them is the digital TV function, which tunes to open TV channels without the need for the internet. The model also brings a digital sensor under the screen and has NFC to use Samsung Pay and Google Pay.

Besides not bringing NFC, the Galaxy M31 brings simpler biometrics, accessed through a common sensor located at the rear. Bluetooth 5.0, the latest version of the standard, is available on both devices.


The Galaxy A51 is available in the market and can be purchased on Amazon at $324 – depending on the offer of the day. The Galaxy M31 arrives at a similar price and can be purchased at $355.

This post may contain affiliate links, which means that I may receive a commission if you make a purchase using these links. As an Amazon Associate, I earn from qualifying purchases.


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