Maybe if you could copy the links of those models from a webshop, so that we can see the whole specification and the price. Or at least the links to the models on the makers' websites.
You can ask people if Sony or Dell is better. Surely there are objective measures to say one is better than another. But there can be many things to be taken into consideration like
- length of warranty (3years vs. 2 years can make a big difference!),
- quality of the parts (watch youtube videos about your model, see if they have typical failures reported by many people),
- quality of the customer service (well horror stories rulez, I mean they are not always reliable, but...)
The reason Dells are relatively cheap is because they are made cheap.
I had a Dell laptop once and it was a nightmare in terms of build quality. After just a year the keyboard felt worn out, The paint was worn off where the palms of your hands touch the case while typing, chassis was "squeaky" and flexing, the display hinge was loose.... In the end the graphics card fried, which was a common issue on that model.
This was about 5-6 years ago, but I would never touch a Dell laptop again.
Sony should be better.
Well, Sony and Dell are both OK but there are many better brands of laptops out there. With the specs you have given obviously the Dell is a must buy but the specs aren't great. If you could include the link to where you're buying the laptop and tell us whats price you're looking at we could help you a lot more.