How are mobile processors different from computer processors

Smartphones have been evolving so fast that now we don't even think about using computer at first for many tasks.

Let's get one thing straight, Mhz/Ghz and no. of cores do not indicate the relative performance of two arbitrary processors.
Earlier they used to be the indicators for the performance but now when we have mobile devices showing similar nos. sometimes higher, it has become really confusing. I am going to talk about all this ahead in this article.

Basically: as the Thermal Design Power increases, the "scale" of the CPU increases. Think of the "scale" between a bicycle, a car, a truck, a train, and a C-17 cargo airplane. Higher TDP means larger scale. The MHz may or may not be higher, but other factors like the complexity of the microarchitecture, the number of cores, the branch predictor's performance, the amount of cache, the number of execution pipelines, etc. all tend to be higher on larger-scale processors.
Now as fabrication size decreases, the "efficiency" of the processor increases. So, if we assume that two processor are designed exactly the same except that one of them is scaled down to 14nm while the other is 28nm, the 14nm processor will be able to:

1. Perform as fast as the higher fabrication CPU.
2. Do so using less power.
3. Do so while dissipating less heat.
4. Do so while using smaller volume of the chip.

Nowadays companies like Intel , Qualcomm , Samsung tend to decrease the fab size and also tend increase the performance a bit. In mobile devices, chipset manufacturers tend to maintain a balance between power efficiency and performance as there is a limit ti the power supply in mobile devices. 

People want their battery last long but also don't want to compromise in terms of perfomance, so manufacturers have found out a solution to this problem too, they have started making their chipsets with two types of cores, 1. Power efficient core (when user is not doing any processor intensive task) 

2. Performance core(kick in when user is doing some heavy task like gaming).

What we see in mobile devices today use a very limited 2-4 watts of power and have 28nm fabrication while a old destop pc of 2012 uses 45 watts of power and 22 nm fabrication.

We can sum up the whole article in these two points:

1. Computer chipsets like i3/i5/i7 are much larger in terms of transistors, physical die area, power consumption, etc.
2. Computer chipsets have to worry less about power consumption unlike mobile processors, so they deliver much more performance when an application demands.

That's it in this article for more advanced information on this topic you can visit various websites and forums where experts explain them in a more elaborate manner