CPU Naming Explained!!
Overview
This blog post is about to explain about the currently using consumer grade Intel CPU’'s .The similarities, differences and their naming schemes.This blog post is not explaining any other competitive CPU vendors like AMD.
Explanation
Do you ever had this question, what the heck is core i3, core i5, core i7?Well I had that question too.This is the naming scheme that used by the Intel to name their processors; AMD Ryzen series has a similar naming scheme (Ryzen 3, Ryzen 5, Ryzen 7) though.Before coming to this processor families, Intel used normally a number with a clock speed to distinguish their processors.(1GHZ Pentium 3 , 3.8 GHZ Pentium 4 …. ).
This was an issue at that time.Because Consumers looked in to the number and expected better performance from the processor by looking at it.But that was not entirely true.Some times the same clock speed processors with different numbers behaved same or better or sometimes the lower number one behaved much faster (Ex:two CPU’s with 1GHZ P3,P4).This is because the clock speed is not the only factor for the processor efficiency.Hence Intel had identified this and the concept of multi-core processors, created this core series CPU Line-up.
Basically nowadays we have three basic consumer grade processors.Those are core i3, core i5, core i7 (and recently introduced core i9).

Core i3
Two Cores
Hyperthreading
less cache memmory
Uses less power
Worse than core i5 (Normally)
Low cost (Baseline)
Core i5
Two cores And Hyper-threading (Normally in Mobile versions)
Four cores And No Hyper-threading (Normally in Desktop/PC versions)
Improved On-board graphics chip on the SOC.
Turbo boost
Core i7
Hyper threading
CPU Cores can be vary from 2 cores to 8 cores(Yeah you were right,4 cores with Core i5 may be greater than 2 cores with Core i7).
Supports 2-8 Memory sticks
And normally uses much power and generate much heat (10W-130W TDP)
Faster Turbo boost
Better on-board graphics
More Cache memory.(Building a higher cache memory is a great factor for increasing the CPU performance; the price tag is higher though.)
Core i9
10 cores as the base model (although we've seen 6 core processors in the new mac-book pro in 2018,it is because a mobile processor i guess).And 12,14,16 and 18 cores.
Hyper-Threading (20-36 threads).So this is good for multi -tasking.Content creation,Video editing,Machine Learning etc.
Turbo boost 3.0
With these i9 processors we can have more SSD’'s more RAM Slots, More PCIe slots etc.
Like always have a better cache and all the other things as well.
But this is so pricey.Staring from $999
Beyond these characteristics, CPU letters and numbers (Model Number) actually means something.

Summary
Processors’ performance cannot just simply measure by looking at the number.There are some factors need to inspect before judging the processor.Core Count,Cache Memory,Features like Turbo Boost/Hyperthreading, Generation ,TDP, Product Line … should take in to the consideration..
