Unlike an angel group, an angel syndicate is an informal group of accredited investors who can select to opt-in or out of individual investment opportunities. Each opportunity requires investors to write a new check, with which they pool together to invest (similar to crowdfunding).
The benefit from receiving funding from an angel syndicate, is that they typically are made up of individual operators who invest on the side vs a group of professional investors. Depending on your business model, these operators may introduce you to your first customers.