If you want a digital subscription to Showtime, you can buy one from Apple, Sony or Roku for $11 a month starting in July.

But if you pay for a subscription to Hulu’s premium service, you can also pick up a Showtime subscription from the video service — for $9 a month.

The 20 percent difference in the two plans, announced today, says a lot about Hulu’s ambitions to build up its TV-on-the-Web service: Hulu says it will pay for the $2 discount out of its own pocket, in the hope of convincing more people to buy its base subscription service at $8 a month — for a total of $17 a month. (Correction: An earlier version of this story incorrectly reported Showtime’s price via Apple, Sony and Roku).

“What we’re basically figuring is that by adding these two services together, we think that consumers are entitled to a discount. We really wanted to be aggressive coming out of the gate,” said Tim Connolly, who heads up distribution for Hulu. “We’re interested in selling Showtime, but we’re more interested in selling Showtime and Hulu together.”

In that sense Hulu, jointly owned by Disney, 21st Century Fox and Comcast, is acting like a cable company, which will only sell you Showtime, HBO or other premium channels if you subscribe to a base package of other channels as well.

HBO’s move to sell its programming on the Web, without requiring any other pay TV subscriptions, was supposed to be a move against that kind of thinking. CBS-owned Showtime, though, has already agreed to bundle its digital subscriptions with other services: Earlier this month it said it would let Sony sell Showtime as an add-on option to its Vue subscription TV service.

But Sony’s Vue is only available in a handful of cities, and may struggle to get traction. Hulu’s subscription service, meanwhile, has proven surprisingly popular, and now boasts nine million subscribers. (UPDATE: A Sony rep points out that people who subscribe to its PlayStation Plus online gaming service will also be able to subscribe to Showtime for $9 a month; unlike the Vue TV service, that offer is available throughout the U.S.)

Even more surprising: The company says that seven million of those subscribers also have pay TV subscriptions. Which means they can already get most of Hulu’s high-profile programming on their TVs, and are paying for the ability to watch on other devices, or because they don’t know any better.*

Connolly says he figures his initial target market for Showtime subscriptions will be the two million people who don’t have pay TV subscriptions.

* Our household accounts for one of those subscriptions. One day I came home and found that my wife had ordered Hulu because she wanted to watch old episodes of “Empire” and didn’t know she could get them from Fox on demand. Since then, we haven’t been able to figure out how to turn off our subscription via iTunes. Which makes us as sad as the people who are still paying AOL for dial-up service they don’t use.