The short answer: there is no meaningful difference. Digital marketing and internet marketing describe the same work, done by the same people, with the same tools. If an agency tells you otherwise, they are selling you a distinction that does not exist.
That said, the two phrases did not arrive at the same time, and there is one small technical difference worth knowing. Here it is properly.
Where the two terms came from
Internet marketing is the older phrase. It came out of the late nineties and early two thousands, when getting a business online meant a website, a listing in a directory, some banner ads and an email list. The word internet was doing the heavy lifting because being on the internet at all was the novel part.
Digital marketing came later and gradually took over, largely because the channels stopped being purely web based. Smartphones, apps, SMS, connected TV and in-store digital screens all became part of the mix. Digital was a wider net than internet, so the industry moved to it.
The one actual difference
Strictly speaking, digital marketing is the broader term. Every internet marketing channel is digital, but not every digital channel runs over the internet.
SMS campaigns are the clearest example. A text message is digital marketing but is not, technically, internet marketing. The same goes for digital billboards and radio ads on digital stations.
For a plumber in Perth deciding who to hire, this distinction is academic. Nobody is choosing an agency based on whether SMS falls inside the definition.
What the words actually cover
Under either name, this is the work that generates enquiries for a local service business:
A website that converts. Sending traffic anywhere else is the most expensive mistake in the category. The destination has to turn visitors into phone calls before spending on channels to fill it makes sense.
Local SEO. Google Business Profile optimisation, consistent business details across directories, and a page for each area you service. This is what puts you in the Map Pack, where most local buying decisions actually happen.
Paid search. Google Ads puts you in front of people searching for what you sell right now. It is the fastest lever available, because you are buying placement rather than earning it.
Paid social. Facebook and Instagram reach people before they start searching, filling the top of the funnel that search alone cannot reach.
Why agencies use different words
Mostly SEO. Both phrases get searched, and different agencies optimise for different ones. An agency that ranks for internet marketing service may barely appear for digital marketing agency, and the reverse is just as common.
That is worth knowing as a buyer, because it means searching only one phrase shows you only part of the market. Search both and you will find agencies the other search hides.
Which should you search for?
Both, then ignore the label entirely and ask for evidence. The questions that actually separate agencies have nothing to do with what they call themselves:
Can they show you a real campaign with real numbers, including the spend, not just the wins? Will you talk to the person doing the work or an account manager? Is there a lock-in contract? Do you own your website, domain and files, or are they held hostage if you leave? Will they tell you when something is not working?
An agency that answers those well is worth hiring whatever it calls itself. One that hides behind the vocabulary usually has a reason to.
How Syvex uses the terms
Interchangeably. We are a Perth digital marketing agency and we are an internet marketing service in Perth, and both pages describe the same team doing the same work. We keep both because people genuinely search for both, and we would rather be found than be pedantic about vocabulary.
What we actually do is narrower than either phrase suggests. We build websites that capture leads, run local SEO that moves you up the Map Pack, and manage Google Ads and Meta ads reported in booked work rather than clicks. That is the whole list.