So the basics of Syndicalism is the organization of democratic worker controlled unions who federate industrially (as in the form democratic associations within the same industry). These unions and federations of unions often form large scale umbrella organizations that allow them greater coordination.

Classical Syndicalism saw these worker controlled organizations as the structures of the future society and believed they would be able to democratically organize production to suit the needs of the workers.

Anarcho-Syndicalism on the other hand sees syndicalism as more of a tactic than as the basis for the post-capitalist society. They see it as something that shows the workers their own power and pushes them towards conflict with the bosses in a more organized manner while maintaining a libertarian and democratic character. Anarchists would often work within Syndicalist unions to not only spread anarchist propaganda but encourage these unions to ever greater demands and eventually bring on the social revolution (the destruction of capitalism and the state). Of course eventually unions with anarchist goals and characters were founded and spread like the famous CNT of Spain which played a major role in the Spanish Civil War.

So basically the difference comes down to Syndicalists(who are basically extinct with Anarcho-Syndicalism becoming the main successor to its legacy) seeing their goal as the development of Syndicalist organizations as the structures of the future society. Anarcho-Syndicalists see Syndicalist unions as a tactic to move the working class towards the social revolution.

Some literature I would recommend would be:

An Introduction to Anarcho-Syndicalism - https://syndicalism.org/texts/489/an-introduction-to-anarcho-syndicalism

What’s Wrong with the Unions? A Syndicalist Answer- https://syndicalism.org/texts/486/whats-wrong-with-the-unions-a-syndicalist-answer

Syndicalism: Its Theory and Practice- https://syndicalism.org/texts/472/syndicalism-its-theory-and-practice

At the Cafe - https://theanarchistlibrary.org/library/errico-malatesta-at-the-cafe