Key Specs
Display and Processor
The Lumia 540 and Lumia 640 both flaunt a 5 Inch HD display with ClearBlack technology for better sunlight visibility and better contrast. Although colors seems slightly more saturated on Lumia 540, but the difference is only noticeable if you place both side by side. Lumia 640 additionally has Gorilla Glass 3 on top for better scratch resistance. Microsoft Lumia 640 is powered by 1.2 GHz Snapdragon 400 quad core chip which is more powerful than 1.2 GHz Snapdragon 200 quad core ticking inside Lumia 540. Both chipsets are good enough to smoothly drive Windows Phone software, nevertheless, this is a big advantage for Lumia 640. Both smartphones have 1 GB RAM.
Camera and Internal Storage
Both smartphone have an 8 MP rear camera, though Lumia 640 performs better. While Lumia 540 can record max 480p videos, you can record 720p HD videos from Lumia 640. Lumia 540 has a decent 5 MP selfie shooter, but selfies clicked from the 1 MP front shooter in Lumia 640 show better and more natural colors. Lumia 640 is a clear winner here. Internal storage is same on both handsets. Both handsets come with 8 GB internal storage which can be further expanded by another 128 GB using MicroSD card slot. Out of 8 GB native storage, Lumia 640 has couple of GB more space available at user end on first boot.
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Battery and Other Features
Lumia 540 includes 2200 mAh battery, while Lumia 640 has a bigger 2500 mAh battery. In spite of the same display size, Lumia 640 is more compact, slim and light weight. Both smartphones have exactly same software. Both smartphones are running Windows Phone 8.1 with denim update preinstalled and are ready for Windows 10, which is expected to roll out later this year.
Conclusion
While Lumia 540 is a very decent Windows Smartphone, Lumia 640 is better. Lumia 640 cannot be purchased from brick and mortar stores as of now. Lumia 540 will eventually get a few price cuts and sell for a lower best buy price.
