The Enterprise D had a holodeck for training, entertainment, and plot contrivance, but on DS9, the holo-projecting room was referred to as a 'holosuite'.
What is the technical difference between a holodeck and a holosuite?
Essentially, there's no difference in terms of the technology. The implication is that a holosuite is smaller and can accomodate one or two people (in a small simulation) whereas a holodeck is a larger space that can accomodate dozens of people.
Additionally, a holodeck is a dedicated space with built-in equipment whereas a holosuite (at least the DS9 versions) are described as 'modular' suggesting that almost any room can be made into a holosuite.
It also makes linguistic sense that a holodeck would be situated on a ship's deck, whereas a holosuite could be any room designated for the purpose. The Enterprise-D apparently contained multiple holodecks as well as various individual holographic environments analagous to a single-person 'suite'.
In an interview for "The Deep Space Log Book: A Second Season Companion" Herman Zimmerman uses the terms interchangeably;
"Holosuites are like the holodeck of Next Generation and we can program pretty much any kind of experience for any kind of location we want to. But what we are doing on Deep Space Nine that we weren't able to do on Next Generation is we see the inside of the holodeck and we see the machinery that runs it. When we did Next Generation we were in a budget constraint that made us do a set that is a wireframe look; it's a grid of squares when the holodeck is not activated and they just see a black void with yellow grids. In the Cardassian holodeck when the lights go off, so to speak, you see the machinery that creates the imagery. It's a step forward for us and it's something we've always wanted to do on Next Generation and we were never able to achieve".
Holosuites are much smaller than Holodecks. But, in typical Ferengi fashion, it's all about the profit. Several smaller Holosuites can realize more profit than one large Holodeck. Think about the analogy of buying bulk items at the store. Buying one large item in x volume container is more expensive 'out of pocket' but with a lower per-unit cost than two smaller items that total the same amount of product. The smaller item is less expensive 'out of pocket' but the mark-up is higher per unit, thereby maximizing profit. Marketing 101.
Holosuites are Ferengi and holodecks are Federation tech, Its implied that the Federation was less advanced in holotech at the time of the first galaxy class ships and that Ferengi had been working with it longer. (early episodes of TNG show it was new tech and was not in civilian use at large yet and Quark talks about the Holosuite King when hes selling fake pieces of him as if hes old and Ferengi live a long time so its implied they had it a lot longer)