Why most of the Russians support invasion of Ukraine since 2014 and hate Poles calling them fascist, nazis...?
This is a complex and sensitive question that does not have a simple or definitive answer. However, based on the web search results, here are some possible factors that may contribute to the Russian support for the invasion of Ukraine and the hatred of Poles:

* Historical grievances. Russia and Ukraine have a long and complicated history that dates back to the medieval times. Russia considers Ukraine to be part of its historical and cultural sphere of influence, and resents any attempts by Ukraine to align itself with the West or join NATO. Russia also views Poland as a historical enemy and a rival for regional dominance. Poland has often supported Ukraine’s independence and sovereignty, and has been critical of Russia’s aggression.
* Propaganda and misinformation. Russia has used its state-controlled media and social media platforms to spread false narratives and conspiracy theories about Ukraine and Poland, portraying them as fascist, Nazi, anti-Russian, and anti-Semitic. Russia has also distorted or denied historical facts, such as its role in the Molotov-Ribbentrop Pact, the Katyn massacre, the Soviet invasion of Poland, and the annexation of Crimea. These narratives are aimed at justifying Russia’s actions and undermining Ukraine’s and Poland’s legitimacy.
* Nationalism and identity. Russia has appealed to the nationalist and patriotic sentiments of its population, presenting itself as a defender of ethnic Russians and Russian-speakers in Ukraine and elsewhere. Russia has also invoked its status as a great power and a victor of World War Two, claiming that it has a right to protect its interests and security in its near abroad. Russia has portrayed Ukraine and Poland as threats to its national identity and sovereignty, and as puppets of the West.
* Leadership and interests. Russia’s invasion of Ukraine and its hostility towards Poland are largely driven by the personal ambitions and interests of President Vladimir Putin. Putin seeks to restore Russia’s influence and prestige in the region and the world, as well as to consolidate his power and popularity at home. Putin also fears losing control over Ukraine, which he sees as a buffer zone against NATO expansion. Putin has exploited the existing tensions and divisions between Russia, Ukraine, and Poland to achieve his strategic goals.

These are some of the possible reasons why most Russians support the invasion of Ukraine since 2014 and hate Poles calling them fascist, Nazis, etc. However, these reasons are not exhaustive or conclusive, and there may be other factors or perspectives that are not covered by the web search results.
But Poland is much better and more powerful then russia.
Better and more powerful are subjective, especially so on topics like these which are heavily disputed.

Poland's population and military is vastly smaller than Russia's: Poland's military including reserve is ~325,000, while Russia's is over 2,000,000. But Poland is a member of NATO, so if Russia were to attack, they would face the full wrath of huge coalition of many countries including the US, and almost certainly lose.

Many people in the US and European nations agree that Poland is a nicer place to stay. And indeed, Poles themselves reported a higher average quality of life than Russians (6.1 vs 5.5 according to OCED QOL index). Poland also has significantly better relations with most other countries, who are allies, while Russia's government is accused of war crimes particularly stemming from the Ukraine invasion. But it's important to keep in mind that better is ultimately a subjective opinion, and some people and nations prefer Russia more.