So capitalism has the tendency to allow free trade. Corporations get more power and pay less taxes. In a socialist economy the economy is controlled by the country. There are corporations but they have to pay more taxes, they can only import or export a certain amount of wares. There are more public institutions in socialist countries whereas institutions tend to be private in capitalist countries.
Let me make an example: Tunisia has a socialist economy because every barber has to charge you 4$ for their job. No more, no less^^ Why? Because the country decides how much a barber should charge. That means there is less competition and every barber gets paid equally for their job.
