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 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.