I didnt know they were two different things -- aren't both a rangetop and a cooktop what you use when you have separate wall ovens? If there is a difference please let me know, I would like to be better informed!
I am planning on getting the Electrolux 5-burner continuous grate gas cooktop. I like how it looks but also how it has a low burner and high powered burner. I have heard good things about it and especially like the layout where the control dials are -- arranged in a semi-circle in front as opposed to on one side like many other models.

A rangetop is different from a cooktop. The simplest definition is that a rangetop is the top of a commercial style range like the Wolf, DCS and Dacor without the oven below them. They tend to have the same size burners in all positions. The controls are in the front of the rangetop and replace the drawer. I mean that the controls wrap down below the surface of the countertop just as if you had a range there.
A cooktop is inserted into the top of the counter and its controls are usually on the side or sometimes in the front but it is on the surface of the counter and cooktop. On cooktops, the burners are always different sizes meaning there is probably one of two power burners but the rest are lower power burners. You can put a drawer at the first level of the cabinet that the cooktop is installed in.

I hope that explains it a little.

A decision of a rangetop versus a cooktop is not really a question of style for me but a question of function. Do you need the extra power of a rangetop versus a cooktop? Are you using Induction which may have an effect on your choices? How large a unit are you looking for?

Good luck!

THANKS for explaining, that is totally helpful to me! I was just referring to rangetops as "professional cooktops" based on how they looked.
I agree with your decision criteria -- for me, I LOVE the looks of the rangetop because of the professional styling, but when I was shopping they all were more than what I needed. They were also more expensive, and the 5-burner Electrolux had everything I wanted (5 burners, low and very high capability, and a grill/griddle included.) So that was how I decided on the cooktop.
Hopefully this will help you too, Jerseyshoremama!

I chose a 36" Viking rangetop instead of a cooktop because I only had 36 inches. The rangetop is roomier than a cooktop in the same space, the telescoping downdraft works well, and it has a lot of power for grilling.