With Campaigns, you can trigger a series of messages based on what Tags have been applied to your subscribers. Using Custom Fields, you can collect more information on your subscribers in order to sent segmented Broadcasts. You would be able to apply tags to your subscribers in a number of ways, including the use of Custom Fields. This article will outline the differences between a Custom Field and a Tag.
A Custom Field is used to collect additional information on your subscribers. This can be used for segmentation and sending Broadcasts to a specific group of subscribers within your list.
For example, if you would like to find out what kind of pets your subscriber has, you can collect that information through your Sign Up Form. Your subscriber's selection would then be listed under their Subscriber Information as a dedicated field.
You can segment your list based on whether your subscriber has choose Dog or Cat from the form. Subscribers who chose Cat be saved as a segment and sent subsequent messages about cats.
A tag can be used to trigger a Campaign to be sent to your subscribers. You can apply a tag via the Manage Subscribers page, through a Sign Up Form, or through the Campaign itself.
For example, if you have different content offers based on which Sign Up Form a subscriber uses to sign up to your list, you can send them a specific series of messages via Campaigns. Let's call these Offer A and Offer B. The subscriber would sign up through Form A to receive Offer A, they would then be tagged with Tag A and start on Campaign A. As you have the trigger set to only send messages when a subscriber joins your list with Tag A, then would only receive the messages in that Campaign.
A subscriber who signed up through Form B to receive Offer B would be tagged with Tag B and start on Campaign B.
You can also send a Broadcast directly to tagged subscribers as part of a segment.