The biggest difference between these two periods is that in 2017 we started with under 1k price but ended with nearly at 20k price, that is the proof that it went up crazy high, nearly as much as x30 in just one year. Whereas in 2020 we have moved from 7k to 23k levels, nearly a x3 increase instead, so 10 times lower amount of increase happened this year.
You might wanna read first post again, as OP didn't compare 2017 and 2020, he is trying to find some similarities between 2017 and 2021 which are more appropriate years to be compared.
It is true that this bull run is different from the previous one and growth looks healthier and more "organic", but there are some similarities between 2016 and 2020, years that should be compared. In both of those years bitcoin halvening happened, and approximately 6 months later bitcoin started pumping, followed by sharp correction. As you can see, once again we see bitcoin pumping, again approximately 6 months after halvening. Since all these things are playing out like in 2016, that makes people think that 2021 will mimic 2017 so you have all those 100k-300k predictions, but whether will history repeat itself we are yet to see.
What we know though is that future is bright and it's been easier than ever to be a hodler.