Without Stalin
With Lenin living longer, Stalin is doomed - propably killed
with this, trotzki will try to keep the revolution ongoing
this leads to more enemies earlier on, so even the nazis will be seen as "good guys" to stop the communists in europe... with this russia will be isolated and hated.
the industrial development will be less sucssesfull, so in ww2 the russians will have less industrial power, no christie to build a certain tank (so no T34.... )
the general situation in late 20ties in europe could be interesting
the germans could be instable and civil war - weimar + nazis vers. communists will lead to an early nazi germany, but with good luck wishes from uk and (partly) france
spanish civil war will be different, less support by western socialists
facism could be seen as "good counter to communism"... some european countries could go communist, like hungary, romania, bulgaria
China will get much support, so even the japanese war from 1937 could come in better light (less conflict with the us of a, if the communists in china getting stronger)
interesting plot