Edit:
There is no meaningul difference between socialism and communism, especially on this aspect (ownership of means of production), which is key to conclude that the system must be authoritarian.
"According to The Oxford Handbook of Karl Marx, "Marx used many terms to refer to a post-capitalist society—positive humanism, socialism, communism, realm of free individuality, free association of producers, etc. He used these terms completely interchangeably. The notion that 'socialism' and 'communism' are distinct historical stages is alien to his work and only entered the lexicon of Marxism after his death"" [1]
The 'distinction' was created by Lenin and the Bolcheviks for political purposes.
"The distinction between communism and socialism became salient in 1918 after the Russian Social Democratic Labour Party renamed itself to the All-Russian Communist Party, interpreting communism specifically to mean socialists who supported the politics and theories of Bolshevism, Leninism and later that of Marxism–Leninism,[53] although communist parties continued to describe themselves as socialists dedicated to socialism." [1]
In Europe, most socialist parties have evolved to simply seek to implement socialist-inspired ideas within a capitalist society and perhaps state capitalism, whereas communist parties stayed on Lenin's line and seek to overthrow the system to set up a fully socialist society.