The sender ID is what appears at the top of a text message in place of a contact name: either a phone number or a short name. A numeric sender ID is a real mobile or other number, and the person can reply to it. An alphanumeric sender ID is a word such as a shop name, limited to 11 characters, and it cannot receive replies at all. Big retailers and banks often use names; many small businesses send from a number.
Two rules shape the choice in Australia. The Spam Act requires every commercial message to identify the business that sent it, and a sender ID alone may not be enough, so the shop's name belongs in the text itself as well. And Australia now has an SMS Sender ID Register run by ACMA, aimed at stopping scammers from sending under the names of real businesses. It covers name-based sender IDs, and messages sent under an unregistered name can be flagged or blocked. If you ever send under a name rather than a number, check with ACMA about registering it first.
In practice
A bakery wants its texts to show "WICKERBY" rather than a number. That fits the 11-character limit. But a name cannot receive replies, so a customer who replies STOP reaches nobody, and the bakery has to rely entirely on an opt-out link in every message. The owner also has to register the name before using it.
Sending from a number avoids both problems. The number receives STOP replies, so the way out works in two ways, and the text opens with "Wickerby Bakery:" so nobody wonders who wrote it. The trade-off is that the number on its own looks unfamiliar the first time, which is another reason the shop name goes at the very start of every message.
In Counter Club
On Local Favourite, texts go from a mobile number that belongs to your shop alone, so a STOP reply comes back against your shop and nobody else's. Every text opens with your shop name and a colon. See your sending number.