Well, thank you very much LoneWolf for explanation and pictures!
I looked once more around here, and this time had better luck, and found some explanations in the thread calleds ''need a light saw'' and ''best small chainsaw'' about my question on the Stihl 021/210 vs Stihl ms200rear handle.
Generally recommendation is:
-if you are low on the money buy an older type of 021 with red trigger because it's not so pricey, but it's around 4.2kg in weight, little more torque with around 2.03 H.P., with recommended 14'' bar (for best usage, it can pull and 16'' bar but with some significant loss in power), the chainsaw is made mostly of plastic and it's in the 'homeowner' class grade, also in some other thread it is said that the muffler port on the cylinder is better/more open on the ones with the red trigger (the red trigger thing is also the case and with 023&025 chainsaws);
and
-if the money isn't a problem, buy the Stihl ms200 rear handle version, you get more of a 'saw, because it is around 3.8kg in weight, little less torque but faster RPM, with around 2.4 H.P., with recommended 14'' bar (for best usage, but it can pull and 16'' bar without some significant loss in power), also it is better built 'saw and it's in the 'pro' class grade.
Now, one more question. Is it a good price for a Stihl ms200 rear handle =around 215 euros (which is around 250 in US $), I saw one here on some local ad's website, it was in solidly preserved state but it was already gone after just two days after showing up. Did I just missed a really good chance, or it was overpriced?