NOTE: to narrow down the question, I will make the following narrowing:
Nazi symbols: salute and the swastika used in clear connection to Nazi (i.e. not this one)
Communist symbols: hammer and sickle on red background clearly associated with totalitarian communist regimes
According to this article, several countries made efforts towards banning communist symbols:
- Indonesia - "Communism alongside Marxism-Leninism are officially banned in Indonesia"
- US - "many states passed laws forbidding the display of red flags [...] United States Supreme Court held that such laws are unconstitutional.
- Moldova - "the law came into an effect in 2012. The Constitutional Court of Moldova found it unconstitutional"
- Ukraine - "the corresponding law was introduced in 2015"
- Estonia - "government signed the draft law to ban politically motivated display of Soviet and Nazi symbols in public place [...] it eventually failed the parliamentary committee on the grounds of the freedom of speech"
- Lithuania - "banned Soviet and Nazi symbols in 2008"
- Latvia - "Parliament has approved the ban of the display of Soviet and Nazi symbols at all public events"
- Albania, the Czech Republic, Germany, Italy and Slovakia - "general bans on totalitarian ideology and its symbols"
- Poland - ban "fascist, communist or other totalitarian symbols" unless used " as part of artistic, educational, collecting or academic activity.". Constitutional Tribunal of Poland found this ban unconstitutional due to the violation of freedom of expression.
- EU - "In December 2013, a group of MEPs including Landsbergis addressed a letter to the President of the European Parliament, in which they requested a ban of symbols of totalitarian regimes."
According to this article, Nazi salute is not legal (or severely limited) in several European countries such as Germany, Austria, Slovakia, Czech Republic, Switzerland and Sweden.
Regarding Nazi flags, this Wikipedia article states:
in several European countries the display of flags associated with the
Nazi regime (see: Nazi flags) is subject to restriction or an outright
Other arguments for the association between communism symbols and criminal acts:
- Declaration on Crimes of Communism (source)
The Declaration on Crimes of Communism is a declaration signed on 25
February 2010 by several prominent European politicians, former
political prisoners, human rights advocates and historians, which
calls for the condemnation of communism.
- Council of Europe resolution 1481 (source)
In the resolution 1481/2006 of the Council of Europe Parliamentary
Assembly (PACE) issued on January 25, 2006 during its winter session,
the Council of Europe "strongly condemns crimes of totalitarian
Condemning the Communist Regime in Romania (1945-1989)
as Illegitimate and Criminal (unofficial report) - this report comes in response to the appeal by the President of Romania, Traian Basescu, that the communist regime in Romania should be condemned on the basis of a report elaborated by a scientifically validated commission.
Death toll - according to this source many people died under communist ruling in many countries: Soviet Union, China, North Korea, Cambodia, Africa, Afghanistan, Vietnam and many others
Question: Given above arguments why banning of communist symbols seem to be harder to obtain than banning of Nazi symbols?