Well the extreme versions have a higher QPI link like my 3960x (that I miss) and usually higher core counts. The Coffee lake uses the 1151 (300) series which give you a better motherboard and more features. The 1151 is like entry level or so, the 1151 (300) series is mid-range or or and the 2066 is high end, just my opinion I am not too into going into the specs too much.
The higher clock rate is for gaming (I had to overclock my i7 860 from 2.8ghz to 3.3ghz to play Arma III), so it will improve gaming where as more cores will improve productivity software. You could go with the 1151 but I would stay with the 1151 (300) series and maybe a low i5 and upgrade in a couple of years to an i7, but I think you are better off with an i7. You can check out some benchmarks at AndTech:
https://www.anandtech.com/bench/CPU-2019/2224 I used to check out Toms Guide but it is full of adds and its not as good as it used to be
https://www.tomshardware.com/reviews/best-cpus,3986.html Actually I think both sites are just full of adds and not as useful as they used to be.
here is a simple i5 vs i7 comparison scroll down to the gaming section, look for FPS or TPS to get a better idea, world of tanks is not going to be anything like 7 Days to Die:
https://www.anandtech.com/bench/product/2258?vs=2250 of course keep in mind it is coupled with a GTX 1080 which is fairly high end and about $600-$700. Far Cry 5, GTA 5 and Tomb Raider seem to be the closest to 7 Days to Die. They really do not add many early access or independent games if any, its usually AAA games that get benchmarked, but then a search might lead you to a YouTube benchmark for 7 Days.
Turbo or Intel Speedstep is another thing that is hard to follow, I turn it off and overclock at a static frequency that is a little less than the turbo frequency. I have always disliked this feature and it can be difficult to benchmark but its probably just me who thinks that.
Sorry for the walls of text but I get into this type of thing and I wish I was the one looking to buy a new PC.
I went to Camp when I was a kid but just because my mom got tired of looking at me. Yeah the code names just get confusing so try matching a code name to a motherboard and that might help, or buy a box of cereal and it may have a special code wheel in it.