They are not different issues. EU laws, directives and regulations are very clearly designed to block and prevent the implementation of socialist policies such as public ownership. Corbyn was elected by the same grassroots, working class Labour members who voted en masse to leave the EU. Thery expected Labour under Corbyn to campaign for Leave, but the Parliamentary Labour Party was and still is packed with centre-right Blairites who are pro-EU. The best Corbyn could do was declare official Labour policy as neutral, and many Labour MPs defied that by campaigning for Remain.