I think the "better" can be incremental in a very small amount. Some things should be better-but unfortunately are not. It can vary so much from brand to brand. You could basically break it down into materials, engineering and service.

Cooktops-
It might be that the materials are a better grade. Heavier grates, higher grade stainless and they might come in colors! Some might be built like a tank, built like a Mercedes, or built in France. When I was looking at ranges, a sales person pulled the knobs off of a couple of ranges and there was a big difference, flimsy plastic vs heavy cast metal in ranges in the same price bracket.

Finer control of the flame-the controls go easy through the range of heat. It doesn't jump from low to high passing the middle ground

There may be higher highs and lower lows as far as BTU rating. Many manufacturers list the simmer in degrees, which is only applicable in one specified circumstance and has little to do with how people cook. Look at BTUs on low and high ends to compare.

Some people prefer one configuration of burner or another.

In ovens, it should be better materials, heavier racks,or better lighting but the biggest thing hopefully would be the engineering. There might be more insulation or features like rotisseries. Gas ovens are a little less complicated, so cheaper and just have an on and off convection fan, which many prefer because it is less to go wrong. Electric ovens, the expensive ones can have as many as four elements with one or two fans that have to be run by a computer board or two. If they are well designed and tested, you will get great results with what you are baking/roasting because you can manipulate where the heat comes from and you can pack the oven and still have everything cook evenly. Often there is an attempt by the manufacturers of electric ovens to keep a narrower range of temperature with some claiming only a 2 degree difference from the set temperature. Normal variance is 25 degrees from the set temperature. Some pump more heat than others into your kitchen.

You would think service is better but apparently from all the posts here that is not always the case. Some manufacturers have terrible service and it will also vary by who you draw when you call someone out. The same manufacturer can also vary. I bought an oven that had a defect and they immediately replaced it. It developed the same defect over time and was out of warranty and they would not even answer any questions without me hiring someone to come out and then he would call and talk to them.

I would look around and see what features would be really beneficial for you in your style of cooking. It is one thing for an oven to have a 2 degree variance but is that really necessary and will you see a difference in outcomes with what you are cooking? Use the search feature on the appliance forum to get an idea of experiences people have had. It is also helpful if you can find a "live" appliance and try it out. You might find you have even more questions to post!

If a premium appliances cost twice as much as a mainstream appliance it does not mean it claims or does have twice the performance. You almost always pay a premium for the last extra bit of performance.

For induction cooktops more money usually means more power which means higher temperatures. The Bosch 800 cost almost as much as a Miele. The Electrolux offers quite a bang for the buck.

Then there are the more subtle factors like whether they have a bridge so you can place a grill/griddle. The noise/buzz they create or don't. The user interface is friendly or not. How good the sensors are recognizing a pan.

The differences among ovens are more subtle. How well insulated are the door and the oven box . The quality of the hinges on the door. How comfortable sliding the racks in and out. How low(proof mode) and how high the broiler can go. Things like how consistent the heat is can't be easily deciphered, it is mostly by reputation.

I have a Gaggenau oven. It is Bosch Siemens Home Appliance Group most premium brand. It has a side opening door so you don't have to reach over a hot oven door. It has an air cleaning catalytic converter that cleans the air of grease before exiting into your kitchen. Many find the controls confusing at first but allows you a lot of control not only on temperature but where the heat is coming from.

Then there is usually longer warranties and better customer service from the top brands.

I have an Elux double wall oven, non-icon Wavetouch, and I love it. I like the easy glide, very extendable racks. I like the controls and all the various settings, like Perfect Turkey, Keep Warm, and Bread Proofing. I bought it based on recommendations here on GW, because it was considered the best value at the price I could afford. The only things that would make me happier would be side opening doors (or french doors) and an air cleaning catalytic converter that would clean the air of grease before exiting to the kitchen. If you can afford the Gag, do consider it. If not, the Elux is good value in the "midrange" models.