When the Lumia 640 was announced last week, I was impressed by the number of improvements it brings over its popular predecessor, the Lumia 635.

Should current Lumia 635 owners upgrade to the Lumia 640 when it becomes available? We quickly compare the two devices so you can make your decision. Watch our video comparison.

The Lumia 635 is a smaller device with a 4.5-inch 480p display while the Lumia 640 improves on that with a 5-inch 720p HD display. The Lumia 640 also features Glance screen, which lets you see the time and other lock screen content when your phone is on standby. That's missing on the Lumia 635.

Because of the bigger display on the Lumia 640, it's also bigger overall compared to the Lumia 635. The Lumia 640 is wider and taller than the Lumia 635, but the 640 is a little thinner.

It's also worth noting that the Lumia 635 does not have a front-facing camera. There's one on the Lumia 640, and it's one megapixel for your selfies. There's a 5-megapixel camera on the back of the Lumia 635, but there's no flash. The Lumia 640 improves on that with 8 megapixels and an LED flash.

Spec geeks are going to like that the Lumia 640 has twice the RAM of the Lumia 635. As you probably know, the Lumia 635 only has 512MB RAM, which prevents the phone to download some apps and games from the Windows Phone Store. That's no longer a problem on the Lumia 640 with 1 GB RAM.

Lumia 640 vs Lumia 635

A lot of the other things are the same. They both have microSD slots, 1.2 GHz Snapdragon 400 processor, Gorilla Glass 3 display, and replaceable battery. We'll have a more detailed review once we spend more hands-on time with the Lumia 640.

The Lumia 640 is expected to sell for 139 euros for the 3G model and 159 euros for the LTE model without any contracts. It's supposeded to release globally in April. What do you think of the improvements over the Lumia 635? Let us know in the comments below!