What characteristic is shared by u. s capitalism and communism

Use of terror as a political tool 
Cult of personality surrounding the leader 
Large degree of centralised political control - often relying on the leader to dictate or mediate between local political leaders. 

However, the differences are vast. 

Stalinism is an economic and political system. 
Under Stalin the means of production, factories, farms, shops and banks, are owned by the state, or by worker co-operatives. 
Workers are paid, "from each according to their ability, to each according to their need", so workers are not paid the same, but according to their skills and their needs. 
Politically, Stalinism was very authoritarian,curtailing free speech and all other political parties - with extra-legal means (violence, disappearances and murders) being used against political enemies, real and imagined. 
Importantly Stalinism was not a racist ideology, believing that workers of all countries share a common culture and will "inevitably" one day unite, ridding themselves of their oppressors - the middle class factory owners and their political allies. 

Communism is an economic and political system. Under most variants the means of production, factories, farms, shops and banks, are owned by the state, or by worker co-operatives. Workers are paid, "from each according to their ability, to each according to their need", so workers are not paid the same, but according to their skills and their needs. Politically communism tends to be authoritarian, banning other political parties - although communist parties operate successfully in many countries within democratic frameworks (look at Italy, France, and India - especially Kerela and Bengal). It is not a racist ideology, believing that workers of all countries share a common culture and will "inevitably" one day unite, ridding themselves of their oppressors - the middle class factory owners and their political allies. 

Communism and National Socialism share very few similarities, anyone who says that they are the same thing knows little about either. 

National Socialism is a political system based on ideas of racial superiority. Racism is central to Nazism, a core belief, other main features are: 

Corporatism - co-opting employers and workers into the state 
Leader principle, cult of personality based on a charismatic leader 
Authority of leader supersedes the usual mechanisms of state 
Anti-communism & anti-liberalism 
Aggressive militarism - 'war is the only hygiene' (Marinetti) 
Extreme nationalism 
Idea that their methods represent a 'higher' form of organisation than democracy, socialism or any other form of government. 
Use of violence & threats to impose their views on society. 
A reaction against the perceived 'ills' of the modern world. 
A belief in the 'volk' or people as having some kind of innate mission that sets them apart from other countries. 

The Nazis were socialist in name only, to persuade workers to join them, not because they believed in free healthcare or a more fair allocation of resources; the Nazis were capitalists. 

Because racism is a central idea of Nazism it is not possible to be a non-racist Nazi - that would be more akin to Fascism, which is militantly nationalistic, but not necessarily racist. 

Fascism is very similar to Nazism, but without the racist element to its ideology. 

Lol at all those who claim Obama, or Republicans - stay in school, you might learn something. 

Death is not a shared characteristic. There have been communist regimes that haven't slaughtered their political opponents - such as the democratically elected communist governments in Kerala, and West Bengal in India, in Nepal and the elected communist mayors of many French and Italian cities.