It's actually quite the opposite. The machines are all similar in specification. My recommendations have been the same for a while.
Intel i5 CPU (any speed)
8GB RAM (any speed)
256 SSD HD (any speed)
Windows 10 Pro
3 Year "Pro/Domestic" warranty & support
The internals on most machines are the same. The differences you pay for are in the packaging, uniformity and support. A entry level laptop is the cheapest plastic they can source, low-end screen, keyboard, battery, etc. A business level laptop, while sharing the same spec, is made much better. Magnesium, aluminum, highend plastic/polymer, etc. They also may have better display panels, keyboards, etc. I also only recommend getting 3 year+ US based support. If you don't get this and have an issue, you will regret it and might end up just throwing away that machine and buying a new one out of frustration.
Right now I recommend Microsoft Surface Laptops for a straight portable laptop only. If your looking for 2-1 (laptop/tablet) it's different. For Dell, the Latitude is a good machine. I don't really like large laptops. If you want something big, get a desktop unit. The new desktop units w/o DVD drives are the size a large paperback book and are fast. They are called "Micro form-factor".
Let me know if you need help.