Pergo is a laminated plastic flooring. Engineered Flooring (DF) by Bruce is a true wood flooring. Let me say more about Bruce and other similiar Engineered Floors ...
There are a few types of EF on the market. Some can have their wear-layer refinished. Some can't. Some use solid hardwood throughout the substrate, others don't. Some use 3 layers, some use 4. Some can be glued or stapled, some both. Engineered isn't usually floated like Pergo but today, who knows.
I like the idea of an EF. Trouble is, unless you're gluing, I don't recommend it for the DIYer. If you read the Instructions, you'll find that you need specialized equipment. And if something goes wrong on a Saturday or Sunday, is the Rental Agency going to be open (and close to home) to help you? If not, remember, you're still paying for the rental EVEN if the equipment is sitting idle. Personally, I'd only use it on a SOLID subfloor or concrete. And if I did use it, I'd make sure my subfloor was LEVEL too. You see, nails/staples tend to work themselves loose if the floor is 'giving' under foot. BUT, if you're 1) gluing, and 2) gluing to a SOLID, FLAT subfloor, the finished floor isn't moving anywhere. That's how pickey I am.
Also, EF floors tend to sound 'hollow' when you walk on them, especially a floor like Pergo where it 'floats' above the floor. I don't like that. For me, if you can find an EF that can be refinished 2-3 times, and it looks just like a 3/4" floor, I'd go and spend the extra $$$ for a 3/4" SOLID floor. To me, personally, it's just that much better all the way around. Pre-finished flooring is excellent material these days. The Factories put 5-10 layers of finish on the wood in CONTROLLED conditions that can't be duplicated in the home. That's good for your floor. Because of this, it will last MUCH longer than floors that are finished/refinished in the home (where 2-3 layers of finish are usually applied.)
Well, once again, I've got cotten mouth. I'll leave any remaining comments on your questions to others. BUT, if you have more ???s, post up. My best to ya and hope this helps.