A flow is a set of emails or texts that sends itself. We set it up one time, and it runs from then on. Each flow starts when a person does one thing, like joining your list, looking at a ring on your site, leaving a watch in their cart, or going quiet for a few months. Welcome, browse, cart, after-purchase and win-back flows cover most of what a store needs.
A campaign is a send you plan for a date. Holiday gift guides, a new collection and a trunk show all go out as campaigns, planned a month ahead and sent on the day.
A text is for the news a client is waiting on, because a text gets read within minutes. The ring in their size is in, the repair is ready, or the trunk show is tomorrow. A client who texts back lands with a person on your team, with their order history beside the message.