Varinderpal Singh :
A generation means a whole lineup of products released in the same time period, based on similar architecture. Architecture means how the product works and its circuitry etc. Each cpu lineup includes core i3, i5, i7, pentium, celeron CPUs. If they all are released in the same time period and have same architecture, they are one generation. Like core i3 6100, i5 6400, i7 6700k, are all 6th generation cpus. The current generation is 7th and has it's own core i series and other cpus.
A motherboard is made for one generation specifically, as the socket on motherboard which holds the cpu is different for every generation. A mobo which runs 7th gen cpus, can hold i3, i5, i7 or any cpu of 7th gen. But not of any other generation.
Gpus are also in generations, while they are referred to as "series" instead of generations. The geforce 10 series is one generation which includes 1050, 1060 and so on.
The previous one was 900 series with 950, 960, 970 gpus.
Amd has it's own generations. Rx 460 470, 480 are one generation.
Gpus all fit in one slot, the "x16 pci-e" on the motherboard. So the socket thing doesn't apply on gpus. That's a cpu-specific thing.
Newer generations are faster and consume less electricity.
Older generations will be relatively slower but cheaper.
So, a 6th gen i3 will be faster than a 2nd gen i5. Similarly, a 7th gen i7 and 4th gen i7 would not be same. because technology advances rapidly.
That is why generation matters.
Easy way to do this comparison thing is just compare the models of the cpus or gpus that you are considering. You'll know which one is better.
There are plenty of sites which do this.
You say there are many sites which do this comparison. Can you name some?
Also, could you please throw some more light on architecture specifically 32-bit, 64-bit, x86 and if there are some othes as well
Generation or series: It can be thought of a bit like automobiles and their model years. Except in this case, each "model year" brings improvements... sometimes minor, sometimes major. So say between 6th generation and 7th generation CPUS, the improvement, everyone gets to see, is a boost in speed. Some model years share CPU socket, many do not, like some automobiles use regular petrol, and others use diesel. Usually the same socket means you can swap out model year CPUs, but they may need a firmware update to recognize the newer model and take advantage of it (or actually use it in cases.) So, it is imperative that you get a motherboard that supports you chosen CPU. (also make sure you get the RAM that is supported as well.)
As to x86 and 32-bit... they are the same, as is x64 and 64-bit. They refer to an internal structure that is common in all modern CPUs. 32-bit is limited to 4GB of RAM, 64-bit can access much more. The instructions used internally reflect that, and are divided up into either x86 or x64 instructions. For the most part, you as a computer user only need worry about that if you are using a 32-bit (x86) Operating System.
AMD had a model year where they actually went backwards, and then every model year since, they tried to fix it, but never got it quite right. This new model year for AMD is a major improvement as they have gotten their CPU performance back on track.
More pertinent to your initial question:
Graphics generations, all modern ones, use the PCIe slots on the motherboard, with usually PCIe x8 being the slowest you want to use. Now, the model year differences here, are power use, how fast they get things done, and what technology they use to do it (DIrectX, OpenGL, Vulkan)... In many cases, the newer generation GPU has the performance of last years model, a "designation", or better, above. So, the NVidia GTX-1060 6GB performs more like the previous generation's GTX-970... or AMD's RX-480 performs similarly to a R9-390 or 390x.
Unfortunately, NEW, with a budget of ₹9000, you only have that one card available. Bump up the budget, and you do get a few more cards at ₹10000.
Edit: corrected wording.