Well, here's a few for a start.
In State and Revolution Lenin wrote of a "scientific distinction" between socialism and communism:
"What is usually called socialism was termed by Marx the 'first', or lower, phase of communist society. Insofar as the means of production become common property, the word 'communism' is also applicable here, providing we do not forget that this is not complete communism" (www.marxists.org/archive/lenin/works/1917/staterev/ch05.htm#s1).
The first sentence of this quote is simply untrue and Lenin must have known it was. Marx and Engels used the terms socialism and communism interchangeably to refer to the post-revolutionary society of common ownership of the means of production. It is true that in his Critique of the Gotha Programme, Marx wrote of a transition between a lower phase of *communism* and a higher phase of *communism*. But Lenin claimed that socialism (or the first phase of communism) is a transitional society between capitalism and full communism, in which there is both a state and money economy. According to Lenin: "It follows that under communism there remains for a time not only bourgeois right, but even the bourgeois state, without the bourgeoisie!... For the state to wither away completely, complete communism is necessary." But Lenin failed to see what this would involve. In effect, the theory of "socialism" as a transitional society was to become an apology for state capitalism.
In State and Revolution Lenin claimed that according to Marx work and wages would be guided by the "socialist principle" (though in fact it comes from St Paul): "He who does not work shall not eat." This was eventually adopted in the USSR Constitution of 1936 and amended to read: "to each according to his work." as a "principle of socialism." Marx and Engels used no such "principle" and they made no such distinction concerning socialism. Lenin in fact did not "re-establish what Marx really taught on the subject of the state", as he claimed, but substantially distorted it to suit the situation in which the Bolsheviks found themselves. When Stalin announced the doctrine of "socialism in one country" in 1936 (i.e. the establishment of state capitalism in Russia) he was drawing on an idea implicit in Lenin's writings.
In State and Revolution, Lenin gave special emphasis to the concept of the "dictatorship of the proletariat". This phrase was sometimes used by Marx and Engels and meant working class conquest of power, which (unlike Lenin) they did not confuse with a socialist society. Engels had cited the Paris Commune of 1871 as an example of the dictatorship of the proletariat. The Commune impressed itself upon Marx and Engels for its ultra-democratic features, which involved a non-hierarchical structure and the use of revocable delegates. Lenin, on the other hand, tended to identify the dictatorship of the proletariat, "i.e., the organization of the vanguard", with a state ruled by a vanguard party. When the Bolsheviks actually gained power they centralised political power more and more in the hands of the Communist Party. Modern-day Leninists claim that the rise of Stalin was due to the ravages of civil war and Russian isolation, but the fact remains that "democratic centralism" can allow dictators to rise to power and all openly pro-capitalist political parties have a similar structure which can allow the leadership to act undemocratically.
-- Lew